Hi Chris!
Although a little dated, this web page has a detailed description of the 5 different sandtrooper backpacks, and it sounds like you're building a #1 pack:
https://tk386.com/backpacks/
Here's another analysis and description of the details that go into the backpack by MonCal:
The top left filter box is actually pretty easy to make, and I can offer the parts for it if you're interested:
Cut out the hole so you can see the filter element, then glue the sides to the base, and the lid to the sides.
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The center bottle is difficult to replicate because you can see the domed shape at the top. There was some discussion a while back about different bottles, but no one has found a definitive item. Check out Strider's build thread using a cut down shampoo bottle:
Photobucket is being poopy and not sharing the photos, so here they are:
It looks like the bottle was cut down by an inch or two, then he used a plastic shim inside to mount the lid.
The top of the bottle has a UFO shaped item, just slightly wider than the bottle. Some folks have used the backing plate for a drill mounted sanding disc:
The rest of the items from your list should be easy to source (I might know a guy )
I've lost the link for the screen captures on MEPD, but you can find a bunch on FISD (after you sign in):
https://www.whitearmor.net/forum/gallery/album/54-sandtroopers-blueray-screen-captures/
Let me know if there's anything else you need help with.
Charlie