That was my first fvwm theme from scratch. My goal was to check the possibilities offered by this great window manager in term of eye candy: I wasn't disappointed.
PEM's Gentoo

PEM's Gentoo
To design it, I've started to create a mockup with Inkscape and try to integrate each pieces under a theme. I was very surprised to be free to do almost every thing I wanted. In case, you would like to do the same, here is the mockup as an SVG file.
If you like the wallpaper, you should find it here.