How do I create a homogenous distribution of a random number of points in a 3D space?

Hello, I'm trying to implement a code, where you can insert a random number of particles and these will be distributed homogenously inside a defined space and shown as dots. I'm having some troubles with the adaptation-process, since the number of rows in each direction (x,y,z) should vary with the number of points we want to insert. Has someone already done this and could help me? I managed to do this in 2D, but I'm having some trouble with the 3D-implementation. Thanks :)