I am planing on building a hand-made pi 2 case either. I worried paper could burn so I'm thinking about metal can or plastic cola bottle.
I dont' know how to cut metal can, what kind of tool could help me?
Plastic could melt, I'm going to put some boiled water into it to try. Not so sure if it works.
Paper or card are fine unless you are exposing the case to a naked flame (which would be bad for plastic too).
Metal or any other conductive material would be a bad idea for a case unless you ensure that the bottom of the pi doesn't touch the case.
Tin snips (which look like very heavy duty scissors) are the standard tool for cutting thin metal like cans.
Plastic bottles will melt at a temperature between 130 to 210 degrees centigrade. Hot glue guns will stick it together.
Building Management Systems Engineer.