I'm thinking about building gadgets that serve parallel functionalities: 1. Relatively small to carry around. 2. Specifically built for one topic of purposes.

I'm thinking about building gadgets that serve parallel functionalities: 1. Relatively small to carry around. 2. Specifically built for one topic of purposes. 3. Can be achieved by a single hacker with on market tools. What kind of tools have you built for yourself? Here are some examples I have in mind: Hardware debugging dongles, rom burning boards and of course Flipper zero itself.