Ready-made switching power supply from an unnecessary computer or laptop board.
In this video, I told where you can get a ready-made adjustable powerful power supply up to 12V. You do not have to make a complex home-made switching power supply.
In laptops, modern powerful synchronous step-down voltage converters are used. I managed to find the LA575 board from a non-working laptop with a convenient location for the converter. In general, there are several of them on the board, for powering the processor, north bridge, video card, RAM, and some others. However, not all of them will do. For some, the voltage is set by applying a combination of logic signals to the terminals VID1 ... VID6.