Here's a coke can Stirling I made, I didn't work as well as I had hoped but it's a starting point! Somehow the flywheel ended up completely wonkey and the bearings keep falling out and it's not very well balanced but other than that its fine ;-) The cranks are made out of a bicycle spoke, I used the thread on the end to screw on the flywheel so it can be easily removed. The piston is graphite in a pyrex cylinder  The target is to build a 1W Stirling generator out of coke cans, a long way to go yet !