This technique shared by [Andy Kong] is for 3D printed lenses, but would probably be worth a shot for any resin prints that need to be made nice and clear. The link to his post on X is here ...

Smoothing the layer lines out of filament-based 3D prints is a common desire ... The UV-curable resin I tested is Clear Standard resin from a Formlabs printer. Other UV resins should work ...

A look at four new photopolymer resins that are unlocking material properties like transparency, biocompatibility and more.