Quad motor holder for 15mm alu tubes, shorter for better cooling - added a new version

The name says everything! I just made it shorter for better motor cooling, works great with my quad!

Added a new version, more robust for better crash stenght. Then in case of hard crash (and broken part) I added a light diaphragm where motor cables go inside the alu tube, so that if you want you can just broke it and take off the motor - change the motor holder with a new one - without messing around with cable etc.