This is a model of the monkey saddle z=x^3-3xy^2. There are two version of the surface, one with the equation, one without.

This model was designed and printed by my WLU summer student Emily Jaekle ('16). See http://mathvis.academic.wlu.edu/2015/07/27/monkey-saddle/.

We printed this on a FormLabs Form 1+ printer. We used grey resin and 0.1mm slices. The model printed really well. (In particular, the font worked out nicely for the equations.) The .form file is included.