Hi
I built one of these a few years ago. I'll dig it out and take a photo when i get a chance. I used a piece of 4" black plastic tube for the displacer cylinder, the studs holding the plates together I made of stainless to reduce heat transfer.
I didn't like the way the crankshaft was all overhanging one side, so I altered it and put the power cylinder on the flywheel end.
good luck with you build.