Any sort of tool, shelter, or device crafted from materials easily accessible to the homeless by a homeless person. An example would be a bench press constructed from two wooden crates, a slab of plywood, some rusty bike frames, and a large metal rod fitted with bags of sand or cinderblocks on either end.
"Is that homeless guy fishing with a stick and some pipe cleaners?"
"Yep. That's some serious bum technology"