I've been intrigued by these sprockets ever since I saw them on Ralph and Sue's Meccano News. I had a few of the tracks (from the later 15 model set) but exactly none of the sprockets. So this was one of the first models that I tried making once I started to get 3D printing figured out.

Thanks to a certain Rust Bucketer going above and beyond (way, way, above and beyond) I got my hands on a real part and was able to put together a pretty good clone. I did make one change; the original part wouldn't take a brass pinion - my 3D printed part does.

The OpenSCAD model and STL files for both the interrupted and continuous tread ring versions are all available at the 3D printable designs for Meccano and compatible parts library.