Cable wrap for the Karcher K2 and K3 models. I have a K2 and the K3 has the same hook. Looks like the K4 and above have a different system. 

Clips onto the cable gland under the hook quite satisfyingly!

Personally I printed with 0.6mm line width and 0.3mm layers but anything should be fine. 
Print with the flat side lying down on your print bed.
Depending on how good your bridging is you might want to turn on supports. I did and they popped out very easily.

Edit: I have updated the model to be stronger after mine snapped. See the V2 file