I can never make Altoids can projects. It’s a like a crazy road block. People have stuck all sorts of projects in these, even an Altair computer! I get parts all lined out I place them, plan out a circuit then, put the project in a regular enclosure or make the circuit to big because I get into it and keep added features.
One of the projects I tried was a BEAM (biology, electronics, aesthetics, and mechanics) robot with one of these cans as it’s body. I absolutely love BEAM robots. They are designed using mainly analog circuits to try and mimic basic life behaviors. In most cases it’s to look for food (light source). Here are two heart beat (solar engine) ones from my stash.
They are great because they are made from junk salvaged parts. The circuits for these is below, it uses a flashing LED. The design is not mine I literally got it from one of those maker style fair activities.