You probably all know the crazy 2x2x4 from Witeden / ShengShouhttp://twistypuzzles.com/cgi-bin/puzzle.cgi?pkey=1913
I never really understood why they used extensions on just 2 faces, instead of on all faces which would result in a more interesting cube, a real (junior) cross cube.
So I decided to build it myself. Main issue is managing to find 3 suitable puzzles (or 2 in my case, since one was already modified) to cover all faces:
As you can see, the white and yellow faces are covered. So we just need to empty the white/yellow face, and replace the normal pieces with extended ones.
Normal pieces corner
Extended pieces corner
Unfortunately, though taking out the pieces is fairly easy, inserting the extended versions on an assembled cube is not. In fact, you'll need to fully dissasemble the puzzle and build it again.
Not a big deal, but getting the last piece in is quite complex. You need to be careful not to move the internal 3x3 edges, otherwise it's back to the starting point. It's based on a 3x3, here you can see the core:
Nevertheless, after a bit of work, here are the resulting puzzles:
And the final result, with better quality pictures. A junior cross cube, in which you can also see (and solve) the supporting 2x2
An easy mod, since you just need to replace pieces, and with a very satisfying result.
Nevertheless you have to be careful when inserting the last pieces, and of course, you will definitely need good luck finding the 3 required sets.