A case I designed to old a pwm board. This 5€ board it's great when you need to use fans that might blow your board transistor (happened 2 times so far to me). So I decided to install this so the feedback from fans don't kill my umo+ transistors again.This PWM 12-24v controller it's very easy to find, they sell it with many names on china shops, ebay, amazon. It's cheap and it works up to 3A without extra cooling. Also it has a nice big ass diode so there's no surprises going back to your umo/umo+ board.Updated to final design. Also added a holder to clip it on umo/umo+. The 'clip' has a space to pass some cables if needed.