Ok now can someone help me with the mod?
You will have to be a bit more clear about the problem.
You might start by searching the forum for posts about the 3x3x5 (you should find many). Also realize that many who have built this mod didn't have anyone to ask and have come to largely the same solution (feet hooking into a hole cut in the top and bottom of the cube). I haven't built one myself but given how cheap a 3x3x3 is I would suggest giving it a shot on your own.