This is my new high tech glue spreader. Yes, its an ordinary cheap hair comb.
Just put a line of glue down and place the comb behind the glue with the top of the comb tilted toward you and pressing down slightly just drag it toward you to spread it, any excess glue will stay on the comb. The top is what it looks for a heavy application with the coarse teeth, and the bottom is what it looks like for a conservative application using the fine teeth.
The glue will not adhere to the plastic comb and after it dries just run your thumbnail acrost the ends of the teet and most of the dried glue just pops off, I use a file comb to clean any residue that is left.