This Monogram Cube is inspired by the cover art of Douglas Hofstadter's book "Godel, Escher, Bach." There are parameters for (up to) three letters and a typeface. The generated cube, if looked at from one of three angles, displays one of the letters.
Open this 3D model in Customizer to select your own letters.
More information is on my blog: http://netninja.com/2013/02/25/a-monogrammed-cube-for-you/
The easiest way to make a Monogram Cube is to load it up in Customizer and select your letters and typeface. If you are more of a tinkerer and want more control, you may download the *.scad file, edit the variables up top, and process it with OpenScad.
There are two typefaces you can choose from. "Blocks" yields better results, but is more stylistic and block-like. It reminds me of some display typefaces from the 20s and 30s. It has smaller overhangs and is easier to print. "Alternate" results in more consistently letter-like, less stylized results, but has more overhangs and is harder to print. It also has a few more incompatible letters.
Note that certain letter combinations don't work well, especially with the "alternate" typeface.
Many letters you select, depending on which face they are on, will have
overhangs that will require a raft with supports. You might be able to skirt
around this with certain configurations of letters (for example, if only one of
the three letters has big overhangs) by rotating on the X or Y axis or even
flipping the whole block upside-down.