I would really like to see a lever machine that was designed especially for efficient home use.

Most people make one or two shots then leave the machine idle for several hours before the next use, so the ability to quickly warm up a small amount of water would be a bonus.

A possible setup is two small (<500ml) boilers and a small fresh water tank all connected in a line, relying on gravity to move the water along. If making just one shot just one boiler could be used (cut off from the others for temp. stability). If making several shots the whole series could be used, cold water flowing into a thermostat controlled boiler, then into the PID'd or constant voltage brew water boiler, then into the chamber.

Henry