I like this simple carriage (https://www.thingiverse.com/thing:2698523) and I printed one for myself while I looked for a fang design. It doesn't have a hotend shroud for a 40mm fan though. This is my design for one.
It has an angled approach to suck air from above and it should reach every fin on your heatsink without blowing any air on the hotend itself.
I used a noctua 40mm fan and it's extra wide so I had to extend the y-stop arm too.