How about a dumpster dive electronics project that uses parts harvested from computers and whatever else can be commonly found in a dumpster dive?
there is not too much to harvest from PCs
- mosfets + inductors from the main board - sometimes discrete logic (almost nonexistent nowadays), if lucky then mosfet driver chips
- small DC motor + brushless motor from a DVD drive
- brushless motor from a HDD
- bigger (4,7uF - 10uF) SMD ceramic decoupling caps (but anything smaller than 1206/0805 makes not too much sense to harvest)
- wires (the ones coming from the PSU)
- the PSU as it is - or for parts.
so it's unlikely you can build a whole project from scavenged parts...