I don’t know if you are aware of it yet, but I found something that would be worth looking into to get ideas on improving your product. It’s called “Voxel Farm.” I haven’t found anything like a stamp feature yet, but improved material rendering did catch my attention.
I believe stuff are made in it’s own application then exported, but it recently came out with a UE4 plugin. I am mostly just interested in the landscape part of voxel though, and not Voxel Farm’s other stuff like it’s voxel dynamic water, it’s blocky Mincraft like architect, or it’s trees. If you don’t like me mentioning competitor products, I don’t mind removing this comment.