need advice on copper mod

[Hodge]

so i want to do a purely mechanical copper mod, i got the 3/4 copper pipe and brass end caps ready to go, for the connector i was thinking a large hole 510 connector with a brass rod or copper rivet down to the positive side of the battery. split the rod in the middle and than use another copper rivet with a insulator and a magnet on the end as the switch with an opposing magnet on the other side with insulator so no hard shorts. question is, what is the diameter of the hole in the 510 connector to do a rod through it? or any other ideas on how to do the switch that dont involve a lathe. all i have is hand tools