My drawing skills are pretty awful, and although I haven't yet had to teach multivariable calculus, someday I will. (And next semester in calculus II we're already doing some volumes by integrating cross sections, volumes and surface areas of rotation, etc). Is there a guide somewhere on how to draw standard 3D "math shapes" (sphere, torus, paraboloid of revolution, intersection of a cube with a plane through a given selection of three vertices, hyperboloid of two sheets, Möbius band, helix...)? I can sort of do a cube by drawing a square partially in front of another square, with some of the edges dotted, and connecting the corresponding vertices. That's about as far as it goes at present.

If there isn't such a guide specifically for math, I suppose I could (with much trepidation) look for more general books on drawing techniques...any ideas for a geodesic to get to math drawing?