So after googling the above title I got 120000 hits in 0.1 seconds ... a quick scan of the first 30 results shows that none so far are home made rca plugs .... I do know people have tried in the past using o rings and the like ...but nobody seems to have made a simple good sounding plug ....except me ! So this is what you can do .... cut a 20mm length of 9mm copper pipe ...I used a pipe cutter the sort that looks like the cutting head of a safety can opener mated with a clamp. cut four of these little fellas ....sit these in cillit bang for a couple hours and then polish. using a dremel or hack saw ...cut a slot 5mm from the end and 7mm long parallel to the end then a slot to form a T with the one you have just cut ...turn it over and repeat you have just made the ground clamp .... its a good idea to offer up a socket and make certain they slide on ....don't widen with pliers let the clamp open under pressure. on the other end make one T shaped slot ...this will form the cable crimp Make a dowel 7mm long and the same dia as the internal dia of the tube ....mine was 7mm ....drill a 3mm hole along its axis cut a suitable length approx 12mm of 3mm dia copper solid core wire to form the centre pin. Fit into dowel and glue [appoxy]. I've used a folded length of 1.5mm dia silver[4n] to build solder the signal wire to the centerpin and dowel and fold back the ground wire . slide this into the copper pipe with the slots crimping down the T section to contact the ground and hold everything in place.. you can add a drop of solder too if you need. ....you can heat shrink if you want job done ! cost £18 for 10m of 9mm copper pipe I'd got the wire laying around to make the pin ....dowel was a couple of quid. how do they sound ......? At least as good as any of my commercial plugs ... but not as pretty