This is a compiled list of school or home project ideas that you can do with your Raspberry Pi, some ideas take longer than others. Slot Machine and Photo Booth take the longest, requiring special parts available online.
The Slot Machine just needs standard push button switches, a 16x14x8 wooden box, a 10×12 lcd screen, a coin dispenser, and a pressure sensitive switch to sense the inserted coin.
The Old Time Photo Booth requires a 24x20x10 wooden or plastic box, a large push button switch, a digital cell phone lens, an LED strobe light, a 3×4 LCD screen and a thermal printer.
If you want more ideas or would like to post your own, go for it!