I am seeing nothing of value on the net to help me figure out any kind of feasible DIY coating. Certainly there must be a way. Seems to me simply getting a layer to deposit would be half the battle. Seems like there would have to be a way to "set" the coating afterwards, lest it would wipe right off. Probably need more time than a few google searches. Haven't even investigated acquiring some raw MgF2 material. Not interested in "multi-coating". An old Rollei lens springs to mind. As far as the OP's question, I believe this thread has already provided the answers with respect to retaining lens curvature.
Originally Posted by E. von Hoegh