Based on a recent discussion with @German_io I looked further into a very high powered, yet DIY-able board. This is the power stage prototype of such a board, using discrete 300A/100V Infineon IPT015N10N5 MOSFETs paired up with Microchip Tech MCP14700-E/MF discrete drivers, high-power current sense resistors and INA225 current sensors.
As designed, the 4-layer PCB is 5x5cm and can carry continuous 30A without any issues, even though the MOSFETs are rated up to 300A continuous. The 1oz limit of JLC cuts the power to 30A before you overheat and melt the board itself.
I’ve ordered the board, will post progress here once fabbed. If the design works, perhaps this could be the base of an ultra-high power board.
Cheesy, but I named the board JACKHAMMER.