I did some pate de verre lost wax casting to make glass armguards a while back but they turned out too rough to wear. 3d printing might be the answer! (Check out my attempt here: https://www.instagram.com/p/Bk45IFqBhbL/?igshid=16fgxi4oubho...)

I'm curious about the too-rough-to-wear bit. Would an extra (leather/plastic) layer below the glass be impossible?

Pâte de verre is typically rougher than kilncasting from a larger billet, because you're fusing glass granules without fully melting them together. So you could get a smoother surface just by adjusting the peak kiln temperature.

But yea, certainly you could add a leather wrap underneath.