Update 4/15/17: I moved the corner hole down so that you will always have two connection on each piece of extrusion.
Design video:
Link to the Onshape files if you want to customize:
https://cad.onshape.com/documents/e19864467367dd560093dc34/w/3f8cc45ae1e95470d198d09b/e/5b348799268d5925f999f83b
Licence: Creative Commons - Attribution - Non-Commercial - Share Alike Category: 3D Printer Parts
The author marked this model as their own original creation. Imported from Thingiverse.