Free-piston Stirling engine

This is a free-piston Stirling engine that I made in 2014. I designed this engine so that minimal metal working is required. All that is needed is to cut two 3" aluminum disks, drill a central hole in one, and cut 4 pieces of tubing and glue them onto 3D printed parts. This is as close to a fully 3D printed engine as I could come up with with no (or minimal if you want to avoid large amounts of filing) machining required.

The piston, cylinder, displacer gland and displacer rod are all brass tubing that you can purchase at a hobby store (sizes used are: 21/32", 5/8", 1/4", 7/32").. The rest are 3D Printed parts that I made on my newly purchased Type A Machines 3D printer (2014 Series 1). The blue parts are all PLA, and the white parts are PET+ (purchased from MadeSolid). The PET was required for the higher temperature on the hot plate (ABS might have been a better choice but it prints with lots of fumes). PLA quickly deforms from the temperatures required to get the engine to run. T