Flat Teardrop

The Teardrop are is a geometrical shape which is used whenever a horizontal hole is printed.
This avoids overhangs greater than 45° at the top of the hole, which are not (or at least not easily and clean) printable on FDM printers without support material.

The problem with teardrop holes is, that they need considerably more space. This can be a real problem, when the main object is limited in size for one reason or another.

Flat Teardrops solve this problem.
The solution is simple. Although overhangs > 45° are a problem in 3D printing, reasonably short bridges aren’t!
So why not just cut off the dead space in the tip of a teardrop?

See http://pleasantsoftware.com/developer/3d/2011/11/29/flat-teardrop/ for more details.