20mm t-slot 90 degree joint

I'm upgrading my prusa2 to a mendelmax, and I didn't want to drill the holes in the t-slot at the top (at uni, no access to decent tools). I saw a 90 degree joint on thingiverse (the one listed as a parent thing), but I wanted to make some improvements:

Built in support - with such a simple part I much prefer designing in support, then printing with no support in the slicer. I find this uses less plastic, and is easier to remove.

The ridge that sits in the t-slot is continuous between the