I needed to make sure that bridges are printed right, before trying to print the x-ends of the Prusa Mendel design. I tried with a hollow cube, but it wasn't a reliable test for many reasons, so I openscadded a more accurate emulation of the x-ends bridges, which only takes around 3 minutes to print with my settings.

1. Try to print the STL
2. If it doesn't do a one layer bridge only, tweak the .scad
3. Take your time to try various bridge settings till you get it perfect.
4. Start your first print of the x-ends with confidence ;)