How could I create a building system similar this?

Hello, I’m attempting to replicate, and create a building system similar to the one shown in the image below.

I already have some of the basics setup (like grid snapping, placing where mouse is, stacking, etc), but I’m wondering; how could you make a system, where you could have handles (the spheres), and when those handles are dragged, the face is extruded.

Thanks in advance, if anyone can find an answer, or some resources for learning this.

I dont think its directly what you want but might be something related.