Whee, vape project time. I decided to rework a few mech squonkers, lining up ModMaker 510 connectors, ancillary stuff (wide positive nuts, the right diameter top washers, and one of those MM 510 tightening kits which should make life much simpler), and some copper sheet to make contacts. It looks like the way to go on the contacts is 22 gauge CDA110, 99.9% pure copper, Hard (which means it'll retain shape, be springy).
One of the
mods needs an 18mm top washer, not a normal item for a US reseller, but the person in the shop is good, will toss one in on his next order from the UK (I'll be buying both sets of connectors, and the tightening kit, from him).
I looked at alternate contact material, but the copper is best bang for the buck, only downside being needing to clean the contacts with an eraser once in a while (normal mech maintenance). Chasing down a 22 gauge hard copper was fun, but I found a US source.
Between excellent contact conductors and modmaker connectors both
mods should be very good performers.