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Field Backpack #3 detailed build


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Hello fellow MEPD members,

I wanted to post a very detailed WIP on my sandy field backpack version 3 to not only record my progress but maybe have this as a "how to guide" for any future sandies down the road. However my original plan was to do the backpack frame but the measurements just threw me off and had no time to even proceed with the frame, but here is the Mortar tube with the materials and how to build it.

(it doesn’t have to be this one exactly but one of my uncles let me borrowed it)


Sanding disk template
(As seen here it can be found at ACE)


Tupperware Pitcher 874 
(This can be found in eBay. If you are going for PO or S.W.A.T the cap must be translusive)


Drill and Plastic cutters


Black drain pipe
(From what I can tell it needs to be about 3ft long from right shoulder to right lower butt cheek and can be found in Home Depot and Lowes)


3M 120 sandpaper
(It can be any sandpaper but it must be between 120 to 180 to make everything fit and perfect)


Scotch brite pads



Everbilt Cap nuts and an AED ¼ x 1-1/2 bolt 


(This can be found in the Home Depot)


Matt Black Paint
(Please tell me if this type of paint is ok since it is matt black and it does covers all of the scratches and logos from the pipe. [see image below])


Trooper bay thermal detonator(for the caps and control I used the plastic scissors and sander to fit them on the pipe)






Before the painting I saw that I would need to use the scour side to make sure the paint would be secure and also sanding the edges so the caps of the thermal detonator can budge in without resist.


Pipe painted with the matt black paint


This is the first drill bit that I used to make the hole that goes on the upper right corner of the thermal detonator control and just for measures here’s the length and here is the sanded end cap, honestly this is my first 1 and what do you think?



Here is a second drill but that I used with the length to layout the sanding disk and pitcher in order to make the radar dish. (I did drill the cap originally but I was off to the right and had to make it longer so please don’t bash me too hard)



Here I also painted the sanding disk and as seen before the disk has letters and numbers and I had to sand paper and use an exacto knife to remove those letters and numbers. Now I used a bolt which was difficult to screw in. Once I had the disk and bolt in place I used a ¼ nut to secure the bolt and disk and that can be manageable with a 7/16 wrench and bracket to keep it in place.


Finally I put the cap in and the cap nut and here is the radar dish. Also not shown but after this installment I used the E6000 to put the thermal detonator control on the top of the pipe. 


Here is the Mortar tube shown in full completion


I hope you guys like this first part of my WIP for the field backpack, part II will be out soon were I would be doing the frame out of a PVC pipe. However, there is still a lot of things outside of this that requires my full attention but hopefully will still do as much work and posting as I can. Plus I think the tube maybe too long let me know if it is ok for a PO or I need to cut about a couple of inches to make the cut.

Also 2 days ago at around 6pm(my time) I have received the items from @crashmann who I can thank enough for helping me out. Once I finish the frame which items should I tackle first?


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I am back here is the first part of my second step of creating my field backpack #3. Where I showing what items you need and feedback on the backpack frame.


¾ PVC pipe


(This can be found in the Home Depot, Lowes and ACE)


PVC pipe cutter



2 Everbilt Flat bars 1in X 48in in diameter and 1/8in thick


(There are two types of bars aluminum and steel, I recommend those who don’t know how to weld or don’t have any welding tools buy aluminum since it is very easy to cut and will hold the amount of items that will go on the backpack. This can be found in The Home Depot and maybe Lowes.)




(This will cut through aluminum than steel and I will be using these bars since I don’t know anything about welding or have any welding tools.)


7/8 wooden dowel


(Can be found in the Home Depot and maybe Lowes but not sure and make sure you get something short in length like a foot or 2 feet)




(I will be using mikelbrierly procedure on making a frame out of a PVC pipe so shout out to him)


Heat gun


A funnel

(Personally, I will be using a plastic funnel wrapped with metal for the inside but recommend a metal funnel, since we are dealing with hot sand.)          


3 bags of Everbilt #10-32 x 1-1/2in screws and 4 bags of Everbilt #10-32 nuts



D-ring hangers


(This is one of the things that will hold my backpack straps I just need to find proper nuts and bolts that can hold it on the PVC.)


Backpack straps


(Now these are leaf blower straps but there comfortable, durable and have no logo so they should be ok for my backpack, right? And this can be found on eBay)


Items(Recurring, see first post):



Paint(there will be more cans of paint I will be getting to act as a primer and the color for the bottom seed trays and bottles)

3M Sandpaper

Scotch brite pads



Now with the backpack frame I am creating there is a roadblock that I am facing and which is the frame measurements and I will share my results for now, which is inches and feet. I took into consideration all of the posts in regards to the frame measurements, however the information was in cm. So, I converted the measurements from cm to inches and I had to ask one of my personal friends to help with the conversion and both results were just too short. However, as I said, this is before I make the frame and would like to get some feedback on the measurements, I tested with my seed trays and the bars(both the aluminum and plastic bars that crashmann gave me), photos on other people’s frames they build and iconoclasta_88 photo on the frame as reference here’s what I have:







The second part of part II will come out soon but for the time bring I would like some feedback on the frame measurements to see if it can work out since I am used to feet and inches and not centimeters.

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So after relooking at the frame measurements provided by Bigwam and having tested it myself(properly) for the second time, I just feel like a brick for showing my take on the frame. My only argument is I had something big going on this week and I was away from my stuff  so I couldn't give an update until now. Finally a picture can hold a thousand words and I thought the backpack frame was going to be long and man was I wrong.

The procedure will commence with the layout of the proper frame in inches for people who uses this type of measurement with slight adjustments and much more information. When it comes to bending the PVC into the frame that can be found in mikelbrierly post which is here if anyone wants to take a look at his frame and shout out to him for making this post anyway the rest of Part II is coming soon. 


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  • 2 weeks later...

After what felt like a long time, I have finally present you the second part of part II of my field backpack build.


I have already noted that I was using mikelbrierly post on making and bending the frame out of a PVC pipe. However there are a few things I want to add that I think will be beneficial for sandies to have so they wouldn’t have to search in an endless rabbit hole.

Proper frame measurements(ignore my bad handwriting)



Here is what the frame looks like when using hot sand for 10 minutes and mikelbrierly instructed but in some cases I still had to use a heat gun which was baffling. To be fair this is my first rodeo so its better than nothing.



I used a heatgun to bend the wall frames as shown here, also I marked where the wall would be bended so its not bended too high or too low. What is also shown is I used a marker to label where I would bend the wall but also where the cross bar should go as well, I recommend this so its not too complicated to put the crossbar on the frame. Whats not shown is I bended a PVC and made a crossbar and was following Mikes process but had made some errors on the crossbar which I am not willing to share (it looks bad).


Shown in part 2.1 there was a 7/8 wooden dowel I cut about an inch or half an inch and used the sander to make it fit inside the PVC to make the cross bar, make sure its not too loose or too tight when you are testing the dowel on the PVC pipe. (note: it'll be up to you how long you want the wooden dowels to be and what type of screw to use this is just an example. However if you want to follow my example than fell free).


The final product displayed on and off my back with a dyed pouch(note: no one was harmed when I was wearing the frame, yes its a BB. I just wanted to see what would it looks like if I had a blaster and I am getting one soon. Its the E-11)





There will be a third/final part of part II where I will be drilling the aluminum bars and painting the frame and adding the mortar tube to the backpack frame. PLEASE let me know if this frame can make the PO cut I have put in a lot of hours to perfecting the frame that was shown on the forum I may not be great but its still shows a lot of effort nonetheless. If this still goes well than sandies can use this forum as a guide to build their backpack, part 2.3 coming soon.


Also what do you think will be perfect to keep the mortar tube on the frame nailing it, using screws, drilling some small holes and use a thin metal wire or one of these two let me know?

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  • 3 weeks later...

I am back with the final part of this long and challenging process of building the backpack frame but here is what I have and how I did it.




Bondo all-purpose putty



Electrical tape



White shoelaces


(you can find these in Walmart)


A ratchet and a 3/8 socket





(The green is for the frame and the seed trays and the black is for the aluminum frames and these can be found in Walmart, ACE, Home Depot and maybe Lowes)


2 zip ties and a thin metal wire



Red fabric


(This will be the foundation of the red support straps and they can be made of cotton, nylon and/or canvas or a bit of both. This can be found in Joann’s and maybe Hobby Lobby )


Chair feet tips


(This can be found in ACE)


Battleship Grey paint


(This was a groveling task to find this certain color in my local area but to save everyone the trouble here are the brands that sell this color and where to find them:

- Rust Tough Krylon Battleship grey – It said to be found in Walmart(online), and Amazon.

- Majic Diamond Hard Battleship grey – This can be found in Tractor n Supply.

- Spaz stix Battleship grey – I can only find this online but it said it can be found in a hobby shop but uncertain where.)


Items(recurring, see part I and part II.1 ):


3M Sandpaper

10-32 Nuts and bolts

Matt black paint

Scotch brite scour side

Aluminum bars


Mortar tube



As seen here the first thing I did was sanded the frame and used the scour side to make sure the paint doesn’t wear off  the frame when I start painting.

Not shown(sorry) I used the Bondo putty to seal off the big holes that were on the side of the frame, seal my mess with the crossbar and put some strength where the wall and curve meet[images below]. And if I’m honest this was the most time consuming than all of the other things I had to do to build the frame.




After I have sawed off the bars in half (like somewhere between 14-15 inches) the next thing to do is drilling bars. There are 4 drill bits that I used but these 2 were to connect the bars to the frame(the left one) and the seed trays(the right one). Also shown is I used a wooden bar to have somewhere to drill down and not shown is I used 2 giant clamps to keep the bars from moving when I was drilling. Once I have drilled the ends on the bars I used the 10-32 nuts and bolt to keep them in place, the 10-32 nuts are tough to screw in, but the ratchet and socket makes it very easy.   




The drill bit on the right will be to make the holes to hold the seed trays, now when drilling the seed trays I would recommend slightly pulling the trigger as I have no clue how sensitive the trays are and its best to avoid any risk whatsoever. Drilling the holes on the bar to hold the seed trays will be the same method as drilling the holes to the frame[see above].



Once the bars have settled on the frame I removed the bars from the frame to prime each of these pieces. When I removed the bars from the frame the nuts and bolts were still on the frame and just taped the bolt thread to prevent any difficulties rescrewing the bars on the frame. Also shown here I would label which bar would go on the frame in order to prevent any confusion down the line.



Then there is the tips the closest thing I could find that can fit on a ¾ PVC pipe was about 11/8 inches and in order to keep them in place I used electrical tape to make it strong and stable I recommend it worked out perfectly. Finally, I painted the entire frame, bars and upper seed trays with matt black and battleship grey on the lower seed trays.



The red support straps were easy to do and thanks to the information thread created by Bigwam and Hausi(link down below) where the straps he found were 10cm/4in in height and 55cm/22in in length. Now I will admit I have never used a sewing machine and down below is the 2 support straps I made and painted black. As for painting the straps I had an airbrush to turn these bright red fabric into a black dull reddish color.



Here is how I tied one of the straps on the frame what do you think.



The Final step is attaching the Mortar tube on the frame, here are the other drill bits I used. The drill bit on the left was meant to fit the 2 zip ties, the drill bit on the right was meant to fit the thin metal wire along with some pliers to give it a grip(This was also difficult to do as well since I needed a flashlight and something long and solid to guide the zip ties and wire but here the result on screen and its complete).




Here is the final result what do you think.






This was a long but satisfying challenge and the next item to work on will be the the radio as I have already started working on it and I am about 50% done. Since I am on the road to become a police officer will the frame make the cut, I put in a lot of hours into this project and I feel amazed on how it turned out.

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Great work so far Ghostie, and great job sharing all the details of your build process!

The red canvas straps with black airbrushing look spot on! Be sure to dirty up the shoelaces so they don't glow in contrast with the rest of your outfit. Also, your mortar tube is a bit long, and should be 30" in length.

Keep up the great work and continue sharing your progress!

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  • 2 weeks later...

Hello MEPD members, here is my progress on the radio for my Field backpack. However, this will be a 2 part as I have a plan to finish the radio and place it to the lower seed trays.


Plastic cabinet feet


(This will be the foundation of the radio feet. As seen it can be found in ACE)


Everbilt 10-24 screws and nuts


(These screws will hold the plastic cabinet feet than the ones that came with the plastic feet. This can be found in the Home Depot)


Masking tape


1 mm by 1.5 mm screws and nuts

(These will hold the microphone jacket in place and can be found in ACE, Im sorry I dont have an image of these screws outside of the assembly)


An arbor and 2 M6 washers


(The arbor[The right one] came with the sanding disk template for radar dish for my Mortar Tube and since I didn’t have the actual antenna with my radio kit but these will make it look convincing. The washers will hold the arbor both in and out of the radio and make it look like an antenna. These can be found in ACE[Again])

Binder clips


Leather hole puncher


Fabric scissors or rotary cutter and cutting matt

(To cut the Pleather)


Radio parts


(This is an Idea of what crashmann gave me, even without the feet and antenna I got resourceful and you'll see scrolling down.)






(This can be found in Hobby Lobby and maybe Joann’s)


Heavy Duty snaps and snap placer



(This can be found in Hobby Lobby and Walmart)


Industrial sewing machine

(I was lucky and found a work shop that had an industrial sewing machine that I could use for free and I have no experience with manually sewing leather and I can imagine it is challenging.)


Gorilla glue and/or super glue


(This can be found in Walmart, Home Depot, Lowes and ACE)




Matt Black Paint


Drill and drill bits



Now this was a challenge to start off but my radio kit came with 5 plastic parts to make the formation of the exterior of the radio and how that was done was I used masking tape to hold off the edges with E6000. Along with the E6000 I used metal dumbbells to keep them in place. However, I can only do one side at a time and wait till 24 hours for the E6000 to dry but I can see why that was important. This was recommended by Crashmann himself and works like a charm.



Not shown(sorry again) was the completed version of the sewed on pleather with the industrial sewing machine, but you can see it here as I explore how will it be displayed on the radio box held by binder clips. The next thing I did was used a drill bit that is about half an inch long and used a round file to expand the hole that would hold that would fit the microphone jacket.



 With the half inch drill in my grasp I used it to poke a hole on the pleather and you can see the result on screen.




After placing the Microphone jacket on the right side of the radio box I used a small drill bit to poke holes that would allow me to put screws and nut in order to hold the microphone jacket.



Once that was complete I started to focus on the left side where I would need to drill in holes that would hold the AUX connectors. However After I have drilled these holes the connectors were able to fit but not completely the connectors had a little gap that wasn’t letting the connectors connect to the wall, so I used a round file to expand the hole horizontally and they fit perfectly.




This drill but I have here was to place in the arbor to act as the antenna for my radio and you will see how it went later on. However, after I have drilled the hole I sprayed the rubber feet, the box, the radio faceplate, 1 of the M6 washer, the tips of the 10-24 screws and the plastic parts that would hold, elastic strap to carry the radio and the dials.(Sorry I don’t have the picture for all of them but there painted and present I assure you.)



After all of the painting I got to start putting everything together on the exterior of the box and how I did it was if I was doing the right side placed the microphone jacket on the drilled pleather hole than I screwed the jacket on the wall to keep it in place. Finally I spread some gorilla glue all over the side and used binder clips, clamps, and some blocks of wood(these will come back later) to hold one side for about 24 hours and will repeat the same thing but just for the different sides.(As shown with the left side as well)



Note: Crashmann did tell me there was one way to bind the pleather to the walls and that was using acetone and ABS shards. This combination is apparently very effective and has the same wait time as well 24 hours. However, I didn’t have any acetone or enough ABS shards to perfect this adhesive but I recommend if anyone wants to try that out than feel free if they don’t want to try the gorilla glue method.


Finally when working on the feet this was a little more complicated than expected before painting the parts I listed I checked how long I needed the small 2 pleather straps and where they would be placed too. However drilling the holes with a 5/16 or 5/32 drill bit to place the feet and the snaps were even more difficult and I made sure they were at least an inch away from the edge but having so much scattered holed I had to putty them up and staring again, this time accurate alignments and depictions of how it should look like.

In the end the straps were about 2.5 inches long to hold the feet and snaps, drilled in new holes on the box, gluing the bottom pleather to the bottom box, poked a hole with an exacto knife for the straps and used a leather hole puncher to guide the screws and snaps onto the radio box. Here is the final result on screen.







Part II of this construction will be putting the radio faceplate together and screwing the radio on to the front lower seed tray with questionable brackets I made to hold them together(when I post a picture of these brackets you’ll see why). Please let me know if this will be ok for my PO since its not from SONIX radio or anyone who sells the real radio, I still want to thank crashmann for providing me such a great product to have for my sandie and I would hate to redo a finished product but at the same time I have no idea if its good or not for the Police Officer rank. I am glad how it came out and look out for more posts down the road. 

Finally in the weapons thread I made a post with question about an E-11 I purchased for clarity so I don't make a mistake on my submission(more info on that post).

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