XYZ test and calibration cube

Wanted a testing cube where i could see which side was +x and -x etc. because i always forget to mark this on my test prints.
The side with X0 has the X emdedded, the X+ side has it outside.
Same with Y.
Also a little overhang test on the bottom.
15.08.2017 Placed the letters more in the middle. they were a bit off