You could design it and have it manufactured fairly cheaply using JLCPCB. Design a simple PCB that is basically a long zig-zagged wire (copper trace). Make sur

You could design it and have it manufactured fairly cheaply using JLCPCB. Design a simple PCB that is basically a long zig-zagged wire (copper trace). Make sure the trace has a fairly high resistance, like a few ohms. Include some heavy-duty connectors on the board. Send the design to JLCPCB; it usually takes a few days and costs almost nothing to have that shipped to the US. Design a base that holds two of the boards a fixed distance between each other, with room for toast, and build an enclosure. You also need a spring-loaded part to hold the toast in place and let you pop it out. Here's an example, sans JLC: https://www.instructables.com/PCB-Heater-Diy-Joule-heating/ https://www.instructables.com/PCB-Heater-Diy-Joule-heating/ Much of the challenge would be making this food safe, and consumer-safe, while also affordable and competitive with a $5 toaster, but that doesn't stop a sufficiently motivated hacker.