Hi - looking to get a start in designing custom water blocks

Doesn't look like these usually get a whole lot of attention, but the link at the top told me to post here so I will.

I'm a software developer by trade with some limited 3D CAD experience (I'd call it "exposure" more than experience... though I have made some small functional 3D prints before) and was intrigued by the modding scene. Looking to see if I can find some CAD models of PCBs and such to try my hand at designing some custom water blocks or other components. Hoping to see if I can turn it into something exotic (and, obviously, preferably very small)!