Practical, no doubt, but pretty unsporting, especially when it’s possible to cast custom lenses at home using silicone molds and epoxy resins. Possible, but not exactly easy, as [Zachary Tong ...
I made a positive prototype out of MDF that I used to make a negative silicone mold. I used total boat deep set fathom epoxy resin and it came out great. Only one country out of 27 did not agree ...