Sound Generator K4401
Based on a pre-programmed PIC 16F57, generates any of 10 sounds, like machine gun, phaser, sirens, race car, etc. in response to pressing a board-mounted pushbutton. The assembly instructions and schematic are here. Runs off a 9-volt battery, has an 8-ohm speaker output and a line level output for driving a power amplifier. A potentiometer controls repetition rate. Yes, the pushbuttons could be replaced by momentary stompers to hack this into a stage effect.