Sourced a bunch of 3d printed knobs for sna fittings. I found it a bit of a pain to turn the fitting and these knobs fit right onto the fitting via a friction fit. There are other designs that have a catch in them to hold on to the backside of the fitting, but these seem to work just fine.
For another run I would reduce the outside diameter. Using sma cables to link up pcb boards, the smaller size would offer better clearance to the mounting board for the pcbs.