Source for quality foam for a DIY case

[Osmosis]

I have a ridged guitar case, 41? tall, that I want for my next rifle case. It looks like decent 4? foam (polyethylene I think is what I want) costs more to ship than the foam itself if I want pieces long enough to fit. Is there any Denver area specialty stories that carry this?
Fall back of course is Amazon but worried I about the quality I will be getting, so any recommendations there are appreciated as well.
TIA

[buffalobo]

Foam Fabricators Inc in Aurora. Been several years since used them.

If you're unarmed, you are a victim.

[Osmosis]

Thanks! I will give them a call.