I was looking for a way to dispense small amounts of solder flux, since the smallest syringe being sold is 10mL, and even a gentle press of the plunger releases huge amounts. I did manage to transfer flux from 10mL to a 3mL syringe using this adapter but found the plunger to be still way too sensitive:
https://www.printables.com/model/599583-luer-adapter
My wife had purchased this five-pen set on Amazon:
https://www.amazon.ca/dp/B075R28129
She only needed a couple and was willing to share. It's a twist pen for dispensing lip gloss and such. The twist mechanism is capable of dispensing tiny amounts.
The adapter has a very snug fit over the pen, and accepts Luer lock needles and tips.
Printed in PLA+ with 100% infill. I ended up using Cura since Orcaslicer was giving me grief over non-manifold (not watertight) bodies on the Luer lock section. I tried using both STL and STEP files provided by wavexx but had no luck with either. Somehow Cura is more forgiving.
The author remixed this model.
Reused model's female luer lock.