Hi Rick,
"""""""""""" It appeared to have 2.5mm wall thickness, if I'm not mistaken?"""""""""

It should have.

""""""""""Aside from that, it's not clear to me what the differences are from draft_v6 to working_file_draft."""""""""""

The original setup was kindof mangled and most likely what was causing your poor stl translations and such. After we get your part done here, I'll make a final video that addresses your initial issues with it, and also try to show you some "Move" and "align" techniques to help out. I know your frustration was looking for methods you were familiar with from other apps. MoI will do those types of moves too, but you may get some good input on that. Lets just do that after so we don't confuse whats going on.

"""""""""The only things I'd like to change from draft_v6 would be:""""""

Here is draft v7. It addresses what you mentioned. The file itself has the "insert" left undone... I've included the Mcmaster part sitting in place (green style).

I've also made a video, with audio that describes how the part is made. I start with draft v6 and re-create the part.

The bottom insert needs to be made. This would be a shape extruded up from the zero point to 15mm, then Boolean diffed out of the part (don't forget to delete the 2 solids in the cavity after this)



I left it for you to tackle? If you are uncomfortable with this, I can do it for you. I just wasn't sure after seeing the part, because we were doing a 9mm radius throughhole, and the part itself seems to be bigger than that? Let me know what you want.