I have seriously thought about building and programming my own washing machine control board on a number of occasions, mostly when I've had an error code or malfunction that could indicate one of multiple causes. The main difference to a regular board would be extra monitoring circuitry to narrow faults down, and of course the ability to create custom programmes. If I did one today, I'd include either bluetooth or wifi for easy upgrading. I even saved the service manual for an old machine for many years, because it had a complete listing with timing for every step of each cycle, with a mind to using it as a starting point. The idea was I could use it to test the components or as a complete replacement if needed.
If I was going to create a whole machine, it would be a front loader, maybe I'd build my own cabinet either out of oak with a turned door surround, or maybe even a stainless steel tubular frame with perspex / acrylic panels. Probably would cannibalise a miele for the cast iron components and drum and tub, as I doubt acrylic would be suitable.