Theres been a few case mod books that have been published over past several years, to accompany your workbench shelf
Yoshi's Mods
PC Mod Projects: Cool It! Light It! Morph It!
Build Your Own High-Performance Gamer's Mod PC
Going Mod
"Case Modding for Dummies" (I hear) is in the works
"PC Chop Shop: Tricked Out Guide to PC Modding" by David Groth. Check out the printable Chapter on Painting,
ftp://ftp.sybex.com/4360/4360ch08.pdf
Maximum PC Guide to Extreme PC Mods