Nickolas Peter just released an awesome circuit bending kit built around a noisemaker keychain. The instructions show you how to make fun mods to the keychain and are very detailed and entertaining to read. It’s called Patient Alpha and he writes:
Do you remember those 80s keychains with the laser noises? They were called the Executor, The Echo Keyller and some other names, but all shared the same sound chip. This page is dedicated to that device reimagined as Patient Alpha. It is an easy toy to circuit bend, and makes for a fun instrument / noise maker. Below are step by step instructions for it, but the approach can be applied to other simple battery-powered sound makers.
So how do you know where to start bending something? You can find which parts of the board are bendable by licking your finger! Open up a battery powered device and run a finger over different parts of the board while triggering a sound. In this case, the board is super simple and there is one resistor to the right of the black blob that makes the patient squirm. The eight pads are for the buttons, and you need to push them with something metal to make that connection – tweezers can be fiddly. I used a finger wrapped in foil next, and ultimately some foil taped around the bottom of a tool.