sources for ground glass

I'm going to make a Goodman One 3D printed camera and one of the things I'm going to require is ground glass. Anybody know how to source these things?

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Or get some glass and silicate, they're fun and easy to grind!

I make my own. You can get powdered carborundum and grind your own glass. I use valve grinding paste on a steel lapping plate.

Here's another option, polycarbonate sheet cut to size, unbreakable, softer than glass so producing the frosted surface takes less time. An additional advantage is that if you want to remove the corners, or add holes, simple hand tools can do the job.

https://www.tapplastics.com/product/plastics/cut_to_size_plastic/polycarbonate_sheets/516

For those who don't have a metal shop a good alternative is wet abrasive paper from the hardware store, used with a rigid sanding block.