mechanical copper mod that needs a tank

[AzIrish]

I made my first mechanical copper mod. I'm using a 18650 battery with 3/4 copper tubing, caps, spring to make her mechanical and 510 connection. What I'm looking for is a nice tank to top her off.
Also I got my caps at lowes and nearly impossible to get a drill hole thru it. If you can give me some advice on getting thru that dang cap, it will really help me. Need to make a few more for friends.
Here is a picture of her right now... Needs a sweet tank.

 

[DonG]

Copper is a "gummy" metal and wants to stick to everything when drilling or machining. Get a step drill or start small and step up drill size until desired hole is achieved. Drill press and vise highly recommended to control feed rate. Mineral oil on the bit will help it cut more smoothly.

 

[asdaq]

+1 on the step drill. Harbor Freight has a set of 3 for ~$10 that I've found to be great and one of these even has a 11/32" step which is ideal for 510 connectors.

 

[AzIrish]

Thanks Don and dag, will hit HF after work and get one.