3DPlot AutoCAD add-on utility we have released a couple of days ago can be used to "materialize" (print) math expressions describing interesting 3D surfaces. This can be used both for educational purposes and for manufacturing nice pieces of technical art.
3DPlot generates 3D mesh surfaces from any math expression of the type Z=f(X,Y) that you encode in AutoLISP. The generated surface models can be visualized in DWF, VRML or in other 3D formats. You can also smooth and thicken most of these surfaces using the AutoCAD modeling commands (MeshSmooth, Thicken) or using the 3DPthicken command. The resulting solid models can be 3D-printed directly from AutoCAD or exported to STL (stereolithography) files. STL files can be used e.g. in the free fabrication tool Autodesk 123D Make to produce cardboard models. So you can materialize your 3D math equations in multiple ways.
Here is an example of Enneper surface cut in cardboard in 123D Make (the source DWG drawing and the STL model can be downloaded from the 3DPlot homepage):