Piston ring compressor tool for air compressor rebuild?

Bill Crowell said
Wow, ACME SS, great answer! Thanks for all the effort. I was able to lower the cylinders over the piston rings by carefully pushing the rings into their lands with a tiny screwdriver, but was just wondering how to do it next time. Thanks again!

Yep it can be done like you did but it is pretty tricky. It's easier when the rods are not bolted to the crankshaft. Good job.