MEGA 2560 D.I.N. rail mount

I am slowly getting parts together to build another 3D Printer, so I ordered a cheap RAMPS 1.4 board from China. I will use a D.I.N. rail to mount the Arduino MEGA 2560 (clone), with the RAMPS board piggybacked to it.
This is a redo of my previous (first) post, which in turn was a remix of Jean Claude's excellent D.I.N. rail mount for the Arduino Mega 2560. All I did was add standoffs to the design, and threaded holes with nut bosses. Unfortunately, somehow, in the process of making those changes, I messed up the holes, and the Mega 2560 couldn't be mounted without some alteration to the fixed locating post.
This time, I downloaded mechanical drawings for the Mega's PCB, and used the dimensions to try to line everything up. I put a 3mm "post" in the lower left corner, setting that hole as an origin. then I set posts at the other hole's positions, offsetting them from the first post as needed. I printed out a low prototype, just a frame and the posts, testing with one of my Mega's. After a lot of trials I finally got a suitable layout. I added standoffs, tried that out, then made holes, then made holes with M3 thread. That version I printed out in full, and it looks good. I then went back and added nut holes on the bottom (but I haven't tried printing that out yet). It all took me entirely too long, but I'm pleased with the result. So far . . .

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