EnXLosure Top Rail Solid mount for nut mounting

The Prusa XL enclosure we mounted on our printer hat some issues with staying on the printer frame. So I modified this mount to enable proper mounting using nuts and also improved the printing orientation by adding a flat face. Adds a little bending load to the enclosure but still works good. For proper mounting of the enclosure you need two, one of them mirrored in the slicer. Additionally, two M3 screws on each sinde need to be changed to M3x25 and 4pcs. of M3 locknuts are needed.