I didn’t want to spent over $100 for a professional intervalometer for my camera to do time-lapse photography with, so I built this one for about $20 (not including the empty Altoids tin).
It’s a snug fit between the electronics, switches, 9V battery and wires, so the rubber bands keep it securely shut. The switch on the bottom is on/off, other switch is for long or short periods between pictures. The potentiometer varies the time from 3 to 30 seconds (short setting) and 30 seconds to 4:30 minutes (long setting). At the other end is a 3.5mm phone jack that the camera plugs into.