I’ve been working on a single vessel brewing system, strongly resembling the one sold be speidel, called braumeister.
Some progress has been made already, and I hope to be able to brew using this system soon.
Short version of what happens in this system: The system consists of two vessels, one 33 liter vessel and another 20 liter vessel with a false bottom.
The larger vessel has heating elements controlled by a PID temperature controller. The smaller vessel sits in the larger and holds grains during mashing. Water is circulated through the grains during mashing to keep temperature even and allow for step mashing. After mashing I remove the vessel and drain it into the larger vessel, where the wort is boiled.