90 Degree corner bracket, aircon frame

This bracket forms the corners of an Air conditioning filter frame. The part is designed to fit into standard size air conditioning spars ~10mm thick.Included model dimensions are width 13.4mm, height 9mm, the arm lengths are 45mm and the center square is 20mm.I've included the SCAD model which is parameterised, so if the fit isn't quite what you are looking for it can be customised. I have played with it a little and it holds up but I can't guarantee that it won't break if push the dimensions too much.