If you love "Junkyard Wars"/"Scrapheap Challenge" you should check out the Afrigadget blog
http://www.afrigadget.com/
I often use it for inspiration
As for welding, there might still be possibilities for arcwelding. There's a handmade welder on afrigadget and numerous other examples on sites like Instructables (another favourite)
http://www.instructables.com/id/Ghet...n_arc_welding/