How to turn a basic object into a BSP

I would like to know how to turn a basic shape object, such as a cube, into a BSP. If anyone knows how to do so, please, could you help me?

why do you want to do that?

U want to too. So I can do the reverse brush thing

You can turn a BSP into a static mesh, not sure about the other way around.

So that I can edit the materials of each side/face of an object’s shape.

Ah thought so, well how would I go about doing that?

just export the mesh, take it into a 3d model app, and make a new texture and uv map