Golden age comic books, of course! Specifically, old and beat up ones. When I design something of this nature, I like to start with a general theme and work my way towards the specifics. For this most recent design, I had spent weeks racking my brain for a satisfying concept. Suddenly, I found inspiration had been in front of me all along. On my desk, I have framed a very beat up copy of Detective Comics #247 that belonged to my father in the early fifties. (One of the few that survived from his childhood.) I realized that was the place to start. Even the color pallette was perfect! So I pulled out my many comic book reference tomes and started to pick the golden age elements I wanted to use. The final result is the site as it appears today.
Easy: A simple parts swap. Little if any paint.
Basic: Some modified parts. Mostly a new paint job.
Moderate: New and modified parts.
Skilled: Lots of new and modified parts. “Frankensteining” often involved.
Advanced: All of the above, plus a great deal of original sculpting.