Anything at all, really. Whatever's needed, whatever comes out when I get bored. I live on a ship, she flies in space? So, we travel and I make sure Serenity's got her workin's in order.
Built a whole transport vehicle outta scraps once. 'Course, I did it with our pilot, Wash-- he's a genius in his own right, really. Painted her up, and she passed right through with the other hospital vehicles. Tricked security an' everything!