Some time ago I went on a glue buying freak-out. I needed glue for a particular project and realized that we were really understocked in general. So I went over to the office supply store and bought about 4 different kinds. They all have their uses but the one I keep finding new uses for is the “ELMER’S® Glue-All™” pens.
They seem to just contain the normal white glue but the real advantage of these things is the applicator tip. Just squeeze and out comes a drop of glue. I sometimes use the tip to help spread the glue around. I don’t have a caliper small enough to measure the inner diameter of the tip but it is about 1.5mm diameter.
Another thing that has impressed me about these pens is that I have had one ‘active’ for at least 3 months and it hasn’t dried out or clogged yet. The cap seems to make a really snug connection.
I haven’t tried it yet but the applicator tip unscrews from the pen part, so theoretically these things could be re-filled.
A pack of 4 cost me less than $1.50 and each pen holds 10.5mL of glue.