OpenBuilds 20mm OpenRail Gantry plate, 80x80mm

This is a model the so called "20mm Gantry plate" for the OpenRail as made by OpenBuilds (it really is 80x80mm). I needed to reference this plate in one of my designs, and hoped/expected to find this in the OpenRails part files from http://www.thingiverse.com/thing:24886

I could not find it there, so I modeled it up quickly. The closest I could get to a reference file model that's not Solidworks was IGES and STL, so that's what's been uploaded ;)

The dimensions are really simple. Holes are