I believe I'm done with messing with the head.  

Today I did a video of the current parts and assembled them, in 10 minutes.

So here, I will answer the questions this will generate:

No, I don't have a good supplier for the brass bits yet.  Everything I've found ready made for Luer lock fittings in metal, with a known ID, is huge and very expensive.  If you are ok with plastic and no ESD protection for your parts, then you can just clip the end off a 10ml syringe, put a bit of heat shrink on the stainless tube, and push it on.

Yes, the right angle drive achieves the target 1.5 degree accuracy across the scale.  No, it doesn't go the full 360.  It now maxes out at around 355 degrees.

The plastic gears, and hypodermic tubing specifications will be linked here when I have it placing parts, which is also when I will post the final design files to Github.

<EDIT>  I mentioned in the video I would do another one about aligning the optics.  Well unfortunately, they were perfect as is and didn't need alignment and so got glued in immediately.  :)  So no video for now, and I'm moving on to bigger fish.  </EDIT>