SmartrapCore Alu Axis Support For Spool holder

Bruno Bellamy's spool holder is my favorite addon for the SmartrapCore.

Now that I'm building a SmartrapCore Alu, the axis part needs a redesign, so here it is :

- The M8 bolt hole is now round instead of hexa (the only bolts I had available have round heads)
- The clip-on part is larger
- There is now an optional m4 hole if you want to secure the Axis Support.

It has not been printed yet, so consider it a work in progress.

UPDATE 2016.02.22 : Trimmed inside part; added m4 hole on