On the top of Glü-Bot glue bottles there's a little protrusion that's intended to hold the cap while you're dispensing glue. This thing doesn't hold the cap very well at all, with the result that the cap often falls off when I'm squeezing out some glue and plops right into the puddle of glue I've just dispensed. (The horror ... The horror ...)

This itty bitty print is the solution. It fits snugly over the existing projection and when you slip the cap over it, the cap stays there until you take it off. The fit of the extender over the existing "nipple" is a secure press fit; no glue needed.

I set "wall loops" to 4 when I print this, but otherwise use standard settings and PLA.