https://www.instructables.com/CARDIAC-CARDboard-Illustrative-Aid-to-Computation-/ https://www.instructables.com/CARDIAC-CARDboard-Illustrative... Although the

https://www.instructables.com/CARDIAC-CARDboard-Illustrative-Aid-to-Computation-/ https://www.instructables.com/CARDIAC-CARDboard-Illustrative... Although the cardboard implementation is kind of the point, I think it's cool that someone made an FPGA version (dead link though, RIP drdobbs.com).