I just dig up Bryce again. Usually Blender is my main program for certain things, but Bryce still has certain advantages. About OpenSea, since most of the people who buy NFTs think of them as investment as well as art, I would think sticking some sort of watermark on your work (especially if it's in the center) will deter people from grabbing your work and sticking it on Opensea.  Considering how much some stuff there goes for, it wouldn't be very smart to buy something that has an artist's name in the middle of it, different from the name of the account that is selling it. It is not a 100% solution, but it does help some. Moreover, to buy on OpenSea you have to use crypto and even if you buy something cheap there would be still gas fees in most cases, which can add up.