I'd like to possibly build some floats. Idon't need anything scale, just need to function and be light enough for a 40 size trainer. I'm assuming wood, foam, and fiberglass construction would be the norm. Are there tried and tested plans out there? Free would be nice. I tried to search the forum without much luck.

Yes search a few of the free plans sites, google me and free plans .......foam core floats will not sink or take on water and upset your flying ...........

Browse around [link=http://www.smilesandwags.com/Floats.html]Jim's RC Seaplane Webpage[/link] for ideas. The Westwood and Linderman articles are classic.

Stan

Here's one article..a little more complicated than it has to be, but very nice floats when finished.
[link=http://www.smilesandwags.com/Floatsite/Foam%20Float%20Core%20Construction.docx]Float construction[/link]

Here is the classic Cunningham article:[link=http://flyinglindy.homestead.com/skisandfloats.html]Cunningham[/link] These are basic, easy to make floats and they work.
You can fine tune the design later.

Thanks for the kind words, Stan