Narrow Cable Grommet

This model is nicely scale-able depending on the size of the hole you need to cover. My need called for one with as thin rims as possible - rest assured it will hold the grommet in place without issue and maximise usable space. 

Simply scale the model in the appropriate manner by the value necessary for your needs.

I'd recommend printing this with a brim if you're not using any additional bed adhesives, as it doesn't have a massive contact area at smaller scales. Supports will not be needed if you print it “upside down” with the retention lip on the print-bed. Otherwise, use your regular profiles.