I spent a day designing something around a flawed model of a linear bearing that I found online and I can't seem to find an actual source for linear bearing models that isn't in .CAD format, so I mocked these STLs up according to the manufacturer's spec sheet (attached).
They are not perfect, but the general size of the attachment surface and screw holes should be good.
They are models, and not meant to function in any way.
I have included a blank 100mm rail in each size and a knockout to put holes in it so you can make whatever size you want.
I have also included a 400mm rail in each size with the holes already in them.
There are MGN9C, MGN9H, MGN12C, MGN12H, MGN15C, and MGN15H in the download.
I have deigned things around the MGN versions and they seem accurate. (last picture shows all three MGN sizes in use)
Be warned, the one thing they wont show you is that a 9mm rail won't sit on a 2020 V-slot aluminum extrusion without falling in the slot. :)
Here's the TinkerCAD link so you can make your own lengths.
https://www.tinkercad.com/things/h427AJdIBpN-mgn-bearings
MGN12-rail-400-with-holes.stl | 638.5KB | |
MGN12-rail-knockout-extension.stl | 634.3KB | |
MGN12-rail-knockout.stl | 634.8KB | |
MGN12-rail.stl | 68.1KB | |
MGN12C-carriage.stl | 440.9KB | |
MGN12H-carriage.stl | 202.6KB | |
MGN15-rail-400-with-holes.stl | 224.0KB | |
MGN15-rail-knockout-extension.stl | 373.1KB | |
MGN15-rail-knockout.stl | 373.7KB | |
MGN15-rail.stl | 81.1KB | |
MGN15C-carriage.stl | 511.9KB | |
MGN15H-carriage.stl | 378.0KB | |
MGN9-rail-400-with-holes.stl | 802.5KB | |
MGN9-rail-knockout-extension.stl | 783.5KB | |
MGN9-rail-knockout.stl | 784.1KB | |
MGN9C-carriage.stl | 195.5KB | |
MGN9C-rail.stl | 58.0KB | |
MGN9H-carriage.stl | 383.7KB |