Hurt my toe.
Designed a cast for it.

Length: 50mm
Inner dia: 18mm
Outer dia minor: 20mm major: 22mm
Holes for air circulation and added some beams for strength.

Inspired by: http://www.thingiverse.com/thing:387792

UPDATE:
Printed this at 112% scale (approx 20mm dia). Slightly tight so didn't fit perfectly. Also, slightly too long so I cut the cast at the seam between the thinner lower and thicker top part. Works ok.

The toe was bent earlier and not part of today's excercise... :D