This is a set of clip on plates to identify sap lines as they come into a main location. In my maple syrup operation I have a bunch of these 3/16" tubing runs that come to one collection point so having the lines numbered helps me keep track of each one's performance.
Another one of my designs that is for a very specific use case, but perhaps someone will need it!
Printed on end without supports. 3 perimeters will make the part just about solid. You'll want to use a flexible filament as the opening is pretty tight and I'd expect PLA would crack.