I just wanted to bump this thread for any plastic bolt owners out there. My friends and I got some plastic bolts on sale and 2 had loose 510 connectors. I pulled all 3 apart, as per boomerdude, I used epoxy to fit the 510 connector properly. I didn't upgrade the wiring, had to resolder one negative connection because it ripped at the bottom base,and used silicon instead of epoxy to seal the device.
If they came with better connectors from the factory they'd have a killer little 18650 mod, but we're happy we spent less than $40 for 3 18650 devices.