This is a simple looking like remix of original fan duct from the X1.
Very simple and fast to print, I made it to guarantee a better air flow and by the way, I can set the blower to less RPM (around 50% maximum) for my prints so my X1 is even more silent than before !
I used a kind of gum (modeling clay) to joint blower and it.
I originally designed it to be printed with PETG as my old PLA duct was melting with high temp from PETG prints, I'm using this since May and it never melted.
Use 235 degrees to melt layers into each other and no fan. Low speed printing. Look for your filament brand retractation settings.