bob, so fiberglass resin is your go to stuff ... ok.
do you put something in the void of the cap, like a dowel that is about the same size? or does the resin hold the t-nut well enough that nothing else is necessary?
otis, i have no clients to worry about. just the wife and myself. we are all about re-using stuff when it makes sense.
what i like about these specific caps is that they are very plentiful, the size is good, and they are not thin flimsy things.
the only down side is that the color scheme in my garage is charcoal and silver, with craftsman red for color. if the caps were red, they'd be perfect.