try contacting the people at Lightblocks (www.lightblocks.com) they might either have something or be able to point you in the right direction.

why non-combustible?

Low cost = prolly not fire rated.

I am a fan of Lumicite and different forms of polygal

3 form
http://www.3-form.com/
Best material I've seen, dont know if its cheaper than glass though

their eco-resin is good for leed,
and you can make patterns and sandwich them inside the material

Polycarbonate, try looking at Polygal and GE Plastics.

Thank you for all your input. 3 form products are really nice, but its self ignition temp is pretty low. polycarbonate(GE/lightbox/CPI) got appox. 1070F, which fall a bit short as well. perhaps, glass may be the only choice for noncombustable.

3 form will run you about $1500 for 3/4" thick sheet (4X8) that does not include shipping. I think their sheets that are 1/4" are about $900. No orders smaller than 1 sheet of 4 x 8. I wanted a product of theirs for a coffee table but $1500 was a bit more than I was willing to spend.

3 form is nice indeed. it doesn't meet fire standards here unfortunately.

you are looking for something less expensive than glass?

seriously - i'm curious - why does it have to be non-combustible?

it's for exterior wall.. code requires it to be noncombustible.

so this is a skin and not an opening - right?

use laminated glass with a colored inner layer

viracon used to have a product called opticolor that you could mix and match inner layer colors to achieve a fair number of different colors.

i do not know if they still support this technology, but someone out there must...

for the plastics, consider the smoke problem that may be worse than anything else about them. some of the newer resins mentioned above have qualified as Type 1 or A materials.

if its for an exterior application, remember that resins and polycarbonates will yellow over time in sunlight. acrylic and glass will not.