Streetcars have always been an interest since I was a kid, riding on the IRC in 1950. I could never find a Z scale model from my childhood memories. First attempt to model a streetcar used a Marklin chassis with a modified N scale shell. This looked ok and ran well, but was a little oversized. When a 3d printed Z scale shell became available, two more streetcars modeling the IRC from Buffalo were built. One was powered with a tiny motor and one was unpowered. The 3d shell was later modified to accept readily available powered chassis and a few more IRC streetcars were constructed.
First model using modified shell with Marklin chassis. Working headlight.