Ultimaker 2 Aluminum Extrusion clone bottom backet

This bottom bracket is for the ultimaker 2 aluminum extrusion clone made by Jasonatepaint

https://www.thingiverse.com/thing:811271

In order to make the frame even stronger merged the bottom and the 2 bottom side brackets into just 1 bracket.
I also increased the thickness of the bracket to 6mm all around and added 1 crew on all branches