Moldable plastic that gets soft from being dipped in boiling water is easily purchasable on Amazon:
http://amzn.to/29XW5NH (InstaMorph)
This is about as moldable as modeling clay; slightly more surface tension so it tends to blobbify a little bit if left on its own.
“drapable” sheets of plastic that can be heated until it droops, and draped over molds, is also available:
http://amzn.to/2a8qaL3 (Polycarbonate/Lexan)
This is a bit floppy even when cold, but very tough.
You can heat this with a hair dryer or in the oven. However, it’s really intended to be used on a vacuum former with a heating table and a vacuum pump to get good definition against the mold.
I recommend against Acrylic (Plexiglass) because it’s quite brittle and breaks easily.
Also: I have a number of Pi-2s and still one Pi-1. I use them mostly for robotics. I use the default Raspbian because it’s the least hassle.
(I also ran Arch on one for a while, because I like it, but the custom hardware support for RPi makes it a little more friction)
I would recommend against running anything server-like (where data preservation long term is important) on the RPi, because the storage options of “USB thumb drive” or “micro-SD card” just aren’t that great.