Steps per mm calibration

My take to calibrate the Steps to mm value.

This is probably not the first model for this task.

Its a L-shaped part in which you can measure a 100mm distance accurate withouth including your wall oversize.

I needed only one iteration and its now spot on. Which means it should measure 100.0mm or simply 3.937 inches.

##**I had an error, uploaded the wrong STL version, it is fixed now.**##