A solution I came up with

I was in a hurry and drilled a hole in a bi-fold door in the wrong place. Now I've got 2 holes (Inside and outside) in the door and it's only 3/16th thick so I can't just patch it. I bought some of the spray foam insullation and made the inside hole a little bigger so the spray tube would fit. I put scotch tape over the front hole and pushed the nozzle tube in until it hit the front of the door. I backed it up and sprayed the foam. I then pulled the nozzle almost out and sprayed some more foam as I pulled it out. I used acitone (fingernail polish remover) to clean the nozzle and remove excess foam fron the back of the door. Now all I have to do after it dries is make a small little indention in the foam and then use wood filler to patch the hole and repaint it.

Seems that this might be a good solution when you have to fill holes in and thin material or in paneling that has an airspace behind it and there isn't something for the patch to adhere to.

Any way, it worked.