Most of the mathematical art produced in the last few years has been in the form of computer graphic images (it's become cheap and easy with available software), but other media are popular too. I've already mentioned 3D printing and machining, and there has been a lot of work in various textile media such as quilting, chrocheting, and embroidery, and origami has been claimed as a field of mathematics. There's been work in more evanescent forms such as soap bubbles and light shows4.
One obvious source of inspiration for artists is geometry, plane or solid, Euclidian, spherical or hyperbolic. Escher created many beautiful examples of all of those categories. But there are many other areas of mathematics which have a visual aspect that lends itself to implementation by the artist: topology, dynamic systems theory, packing theory, and so on³. Recently nearly 20 years of work by a loose cooperative of mathematical artists (or is that artistic mathematicians) including the science fiction writer Rudy Rucker, ended in the discovery of a 3 dimensional analog of the Mandelbrot set and the creation of some really beautiful images.
If all this sounds interesting, you can follow the link in the title of this post to a site of links to a number of artists working with mathematical images of all sorts. I plan to blog more on this subject, and say more about specific artists. To get you started on some of the do-it-yourself possibilities, here's a miscellany of books and links. Some of the books, especially the ones on theory, are rather expensive, but you can find them at many public or university libraries. The book links are to bookdepository.com.
General books on Mathematical Art:
"Fragments of Infinity: A Kaleidoscope of Math and: A Kaleidoscope of Mathematics and Art" by Ivars Peterson
Theory or Mathematical Art:
"The Visual Mind II" by Michelle Emmer
"M. C. Escher's Legacy" by Doris Schattschneider
The Home of Mathematical Knitting (sarah-marie's mathematical knitting pages)
"Making Mathematics with Needlework" edited by Sarah-Marie Belcastro and Carolyn Yackel
"Curve Stitching: Art of Sewing Beautiful Mathematical Patterns" by Jon Millington
The Geometry Center Download Page
¹ It certainly won't surprise any artists who took a course in perspective drawing.
² I wonder just what percentage of the world's CPU cycles has been involved with displaying some part of the Mandelbrot set.
³ For more than a century a war has been waged within mathematics over the legitimacy and relative importance of visual intuition in mathematical research and understanding. Coxeter fought for many years for the use of diagrams and visual insight, often against the hydra-headed Nicolas Bourbaki. Both art and mathematics were the benefactors of that battle.
4 There is a group in Germany that projects light shows onto buildings.