PyraSied is a local Dutch company that specializes in plastics and acrylics. I recently saw a sample of their PyraLED PMMA (acrylic) diffusion sheet and was supremely impressed by its diffusion properties while maintaining decent transmission. Specifically the PyraLED 3 in 10mm thickness. It is the best diffusion I’ve yet seen from any supplier.
Thanks BeersNielsen for finding this material!