Mistakes? Heh. Just read my thread

. It's chock full of em!
Seriously, though. I look at mistakes as just reasons to rethink what I've done, or improve things.
For example, I put my CP together, used a gold ink to stamp the artwork on and then thought "I'll spray this with clear coat to protect it"
Yikes. The clear coat came off in sheets, after I'd completely assembled the cab.
I had to completely disassemble the CP scrape off the clear coat, use alcohol to get all the remaining artwork off. But then, since I had it all torn down, I added indicator lights for all the buttons, vastly improved the stamping technique and designs, and found a much better clear coat, so, a little more work, a lot better result.