I'm going to do some experiments with a pressure chamber requiring me to get electrical signals out from a strain gage. That means I need at least 4 wires. Directly in the chamber wall, there's a ball valve connected using a 3/4" NPT male end. I'm thinking of replacing that section with a T-joint - one end goes into the chamber wall, one end into the ball valve, and the third end will be capped. Previous tests haven't shown many problems with the NPT connections throughout the system, despite the pressure being 800 psi. My idea is this: I want to drill small holes in the cap, then use copper nails as the pin feed-throughs. The head of the nail is on the inside of the cap, so it's pushed outwards by the pressure. The shaft is wrapped in electrical tape, to prevent conduction to the cap itself. Then, the wires would be soldered on either end of the nail. Lastly, of course, an o-ring right under the head of the nail provides the seal. I've been staring at this idea for awhile now, and feel like I must be missing some obvious problems, because it seems too easy. Does anybody have some feedback on potential complications? And also, any tips on O-ring selection?