We made force cubes
Yesterday Josh made 6 force cubes from 6 regular 3x3 stikerless cubes. The process was very interesting, so I decided to record it here.
First, we prepared six regular 3x3 IDENTICAL STICKERLESS cubes:

Then we took them apart into many kinds of pieces: cores, center caps, corners, edges.

Cores

Center Caps

Corners

Edges
Then, we sorted the center caps by color and put each group onto a core respectively. After that we got this:

Single Colored Cores
The next work was to sparate the corner pieces and edge pieces into smaller parts:

Separated Corners

Separated Edges
and reassemble them into single colored corner/edge pieces:

Single Colored Corners

Single Colored Edges
At last, we assembled the force cubes:

Force Cubes
And, Josh also got some other ideas, checkerboard cubes which can never be scrambled and sandwich cubes:

Other Cubes
That's pretty much it, by the way, Josh has a big collection of cubes which is listed on his website.