Some people really activate their brains once they get locked up. The things I've seen people construct from literal garbage in prison. Tattoo guns are a popular one. Obviously half the population has a way of making some sort of device analogous to a car cigarette lighter in prison by finding staples, bits of wire, foil etc that they can stick in a 110V outlet to heat up and light their drugs from. Necessity really is the mother of invention.

A friend and I got split up into different cell blocks because we were helping each other with litigation. Knowing this would happen we'd come up with a way to communicate across the facility. We had these 5x5 grids of letters, no "K", where 11 on the grid was A, 15 was E, 55 was Z etc. They had these touchscreen commissary kiosks where you could order food. The quantity of each item allowed up to 4 digits, e.g. 9999. So that gives you two letters. 1121 = AF for instance. We'd start at the top, Beef Noodles, 1121. Chicken Noodles, 2412 etc and work through the menu. We shared our login IDs with each other. We'd place these huge orders into the cart but never checkout. Then we'd log in to each other's accts from our separate cell blocks multiple times a day, read our messages and write our replies. Got caught eventually, 10 days in the Hole. I FOIA'd their investigation and it was very amusing seeing the report from the facility "Intelligence Dept" trying to decode all the messages.