Fitted Sheet Clip

What is the one thing you yet lack which will complete your quest for domestic bliss? A cylindrical clip to keep your fitted sheet cliped to your mattress. I saw these at a grocery store for $5 for 4. Figured I could design and print them for less than that.

And before you suggest it, yes this really should be a parametric all purpose cylindrical clamp. Then you could use it for clipping cardboard together to make a cheap cardboard planetarium. Feel free. :)

My blog if you are interested.