Ender 3 LM2596 Case

Remix of BradyZ's case.

It did not properly fit my specific buck converter (posts did not align with board):
http://www.amazon.com/dp/B07N3QT628

My changes/customizations to bottom (base):
1. Adjusted location of posts/standoffs
2. Changed conical standoffs to cylindrical
3. Reduced diameter of posts for looser tolerances
4. Removed labels for +- and input/output
5. Widened depth to allow for a little more room for buck converter

My changes/customizations to cover (top):
1. Added window to view LED readout of buck converter