This was really pretty fun and easy to make, and booms like crazy. About twenty bucks.
   Pick the right shovel, with a wood cross-handle, and a workable action, fourteen bucks at an Ace Hardware retailer. You need a tuning key, and a pickup, and wires. You have to grind flat and drill the cross-handle to put in the tuning key. There's a groove in the steel handle to guide the string. Drilling the steel spade is the biggest chore. Turn an old pick-up sideways under the string so all six magnets hear it, and bolt it in place on the spade. A thinner flatter pick-up makes it easier to get the action right. The wiring is housed behing the spade in a video cassette box. The string goes through a hole in the spade. You can do control knobs if you want, but why give a kid the option of fooling with the knobs. You can place frets with key ring metal. The heavier gauge at the nut and again at the octave (to compensate for the wood-to-steel bump where the spade starts). Also, I've never seen anyone do it, but a slide helps for some bass parts. My kid likes slide sounds but they're hard on his fingers, so I gave him a glass slide to play with, metal is too noisy and dull. A shiny pickguard is nice.
   There's more you could do, but by then you've found a pretty light Peavey, and there aren't THAT many songs that involve digging with a shovel.