This toy design from 1931 is in the public domain... I bought a set and scanned one, this should be pretty much exactly the correct dimensions!

Don't have a 3D printer, you can now order them directly from Shapeways ($31.96): http://www.shapeways.com/model/736502/bill-ding-clown.html

See http://www.billding.com/index.php/bill-ding-history

This thing was made with Tinkercad. Edit it online https://tinkercad.com/things/dvbWYGHzDEk