I use 1/16" thick petg or lexan.

FYI:
Lucite and Plexiglass are trade names for acrylic.
Lexan is a trade name for polycarbonate.
I've never worked with PETG, but from what I understand it is more flexible than polycarbonate, but has a lower impact rating.
If you need to glue up any of your parts, acrylic cement will work on polycarbonate. I recommend IPS Weld-on 16. Weld-on 4 is faster, but SO much harder to work with.

HTH's

Yes. Actually, I've never seen it any other way. But then I've never looked for it in colors or opaque. You can get 1/8" at the warehouse home improvement stores. Not sure about 1/16".

Edit: I just checked lowes.com, and they have Lexan in .093" thickness. That should be close enough to 1/16"

ya mostly clear, and if you find the colord stuff for cheap let me know, its super spendy- ive got much better deals than the box stores from some sign companies on ebay, lots more thickness and sizes to chose from too.

Papilio makes an inkjet backlit film that might work. http://www.papilio.com/inkjet%20adhesive%20inkjet%20backlit%20film.html

OR their white water slide decals

I am pretty sure you can't laser cut or flame polish polycarbonate / lean as it releases a toxic cancerous gas

I've seen no mention of anything toxic, but it will ruin the part. Use solvent after sanding to polish.