I recently used the 3m 8115 panel adhesive to bond in some patch panels for my wheel wells. This adhesive works great but the applicators cost around $250.00 bucks.
I came up with a way of using (2) $2.50 caulk guns to build my own applicator. It works well you just need to be patient and allow the gun to push the adhesive out. If you push to hard the bars slip.
Heres the steps I took
1. I took one of the guns apart and used the bar for the top cylinder of adhesive.
2. I turned down a small plunger plate and attached it to the upper bar. ( you could use the caulk gun plate and just cut it down )
3. I then welded a small sheetmetal guide to the other caulk gun to guide the upper bar.
4. I then tacked the two bars together.
It is a simple cheap solution that works well and figured I would share it with anyone interested. There is a picture attached and if there are any question or if you want more pictures you can email me at firstname.lastname@example.org