This models shows the paraboloid z=x^2+y^2 with its formula. There is a second .stl file giving the surface without a formula.

This model was designed and printed by my WLU summer research student Emily Jaekle ('16). See http://mathvis.academic.wlu.edu/2015/07/20/quadratic-surfaces-paraboloids/ for more information.

This object was made on a MakerBot2X. We used the following settings:
2 shells
0.20mm layer height
10% infill (hexagonal pattern)
Color matched supports
Raft on

We printed the surface upside down. This worked really well.