A "standard" Singer 66 plate is .085 thick. Yes, you can get plexiglass (lexan, or "acrylic sheet") in various thicknesses. I used what I had on hand, which was .100 thick, and the material has to ride over it. However, you can get it in thicknesses of .08, .093, .118... I would have measured it with my caliper if I were buying new, but knowing now that the Singer plate is .085 I would have tried either .08 or .093 thickness. They sell it at Lowe's, Home Depot, ebay...An 18x24 sheet runs about $10 plus tax--I could make two dozen plates out of that, give or take a mistake.