The Urban Proof crate I had bought before my 3D printer time. I had mounted it with hard rubber pieces as spacers on a Racktime Snapit adapter.

I replaced the rupper pieces now with mount plates. With the two new mount plates, the crate now holds much better on the Racktime Snapit adapter, it also looks better (even if it is under the crate, and you do not see it most of the time).

In the crate must be drilled two holes for the adapter in the middle. At the adapter you have to cut off a bit at the rear bracket at the screw holes on the edge (see photo).

Created with FreeCAD 0.21.