3D OnShape Model for Stamped Metal Part Ended

I need a 3D model (OnShape or similar) for a stamped metal part. It is a cover for a 4" square electrical junction box that transitions to a round 1/2" deep mud ring. The round mud ring is sized to accept European electrical switches with 60mm screw spacing. The existing part has a rectangular mud ring, which I want changed to round. The starting point is the file at this OnShape link: https://cad.onshape.com/documents/816a507bf2329d0250ed7d75/w/aeca433e5e1d810e44c4515a/e/96ca660fc327722b52c35d78. Attached below are two photos, front and back, of what the part should look like, but with the 60mm screw spacing. The photos are for a similar part made for US-sized devices, but the concept is the same. This is a one-time request with a prompt deadline. An OnShape expert should be able to do it in under two hours, I'm guessing. read less