If you haven't tried a Roto Zip spiral saw you should check them out!
I have used mine at home for about six months now during a remodling project and it was great for wall board and such.
I have been using it lately on my cobra project and it is so easy to cut holes in fiberglass but the neatest use I have found is cutting aluminum panels for the engine bay. With the correct cutter it makes cutting out holes in the panels so easy and swift it is actully fun.
Roto Zip website
Scott S