My Pipe didn’t fit the drill I have
The 1/2″ O.D. is important because this is where most commercially available drills max out at. Plus any larger and you run the risk of the hole being too loose.
What type of pipe is it
I used some rigid aluminum pipe with thin walls, 1mm max. Aluminum because it cuts and sands easily.
I don’t have a Dremel tool
A square file or hacksaw should work too. You’ll need a way to clamp it though, you won’t have success using one hand and you greatly increase risk of the saw slipping causing injury.