Anybody used the expanding foam you can buy from the diy stores, in aerosol form.

Sorry for the late reply. Just wanted to say that I have used expanding foam to make a canoe plug. Initially, I had made the error of building a female mould without a plug... I know, just ridiculous. Anyhow, I used three cases of 750ml containers to fill-in the would be female mould. It worked perfectly except that if you spray too much in one go, the interior part of the foam mass will not expand. Otherwise, by spraying layers of maximum 10cm, waiting for expansion and dry, you can add as many layers as you want. Sanding is a breeze and you can then cover the plug with body filler before finishing with getcoat.