I found that I can make various 3D from 4 basic blocks

There are four basic blocks. I made curved surfaces by combining these blocks.

I am thinking that we can create various 3D easily like voxel modeling software

Very cool. If you really want to go down a rabbit hole, check out signed distance fields, or SDF. It’s shader based, so a bit different in execution, but still the same principle. The crazy things people can do with just a few basic primitives is bewildering. http://mercury.sexy/hg_sdf/ is one such shader library. Super fun to play with!