Yeah, STEP files are great. They can be imported into FreeCAD, which is my main CAD tool.
The .step file is larger than allowed. Is there a particular cloud service people prefer? If people want actual dxf files of certain parts, I can do that as well. For my linear rail block mounts I used 3/16" thick aluminum angle. I milled them with a jig with my old Ox. https://www.youtube.com/watch?v=L7L13razafU
That video explains how you got the mounts I asked about, thanks!
Also, pretty cool how you made the jig for them.
If/when I were to try to replicate it, this video will be helpful. So would STEP file(s) or DXF files.
If a single STEP file is too big, maybe you can upload several smaller ones?
Ah, I wish I could set different size limits for different kinds of files. 
I think any service that just lets you download works great. Plenty of folks have shared links to google drive, but anything like it would work too.