Neville,
I built my Hs-129 fuselage by laying up glass over a male foam plug, then removed the foam from the inside. Probably less work than a plug and a mold, but heavier. I have made several smaller plugs from cheap stuff like pine or foam and then finished with a relatively thick layer of Bondo polyester putty. You can get a great finish with the
Bondo and primer.

Over on www.rcscalebuilder.com there is a Fury build that includes a mold for the front end. Check the "scratch built" set of threads. Being done by Gwyn Avenell of New Zealand who I met at the World Scale Championships in Sweden 2006. He built an SBD marked as one flown by his neighbor in WWII. Turns out his neighbor probably flew some of the same strikes as my Father who was a Marine SBD gunner on the same island at the same time. Dad had lots of respect for the Kiwi's. Small world, huh.

Chuck Snyder

Now, for many years I've had a desire to build a Hawker Fury 1. That is the classic 1930's biplane always with the highly polished cowling panels. My intention would be to make the whole front fuselage from glass fibre! Now, as this model would be about 1/5 scale, this would be rather a large plug? To make it from balsa would need a mortgage I thought about high density foam, then glass fibre on top, but we're getting expensive again. Has anyone made a large fuselage plug, I'm not worried about putting detail on it, this can be done with litho plate panels later. Jelutong is the pattern makers wood of choice, but hard to to obtain here. Any Ideas?

The plug can be any old thing that'll hold up to pulling the part (or female mold) from it.  Weight doesn't matter, so balsa is a poor choice.  Use foam if you like how it carves -- polyurethane may be good, as it's easier to sand than styrofoam.

I'm surprised at your statement about 'glass being expensive on the male plug -- but then, I haven't priced it lately!  You _don't_ need to use the same glass for the plug that you'd need for the fuse!  I'd go to my brother's fiberglass shop and beg some from him; if not I'd go to Tap Plastics and see what the absolute cheapest stuff they had cost.

Alternately, consider making the plug out of whatever wood you can scrounge (i.e. old pallets, studs from you ex-wife's house, etc.), cut to rough shape & glued together, then slathered with polyester body filler (Bondo in the US) and sanded to final shape.  Get some polyester catalyzed primer to squirt as a final coat (or find a paint shop that has it) -- that stuff sands easy, and is strong enough that you can wax it and pull a part off of it.  You may well damage the plug, but you'll get a good part.

If you want to make more than one, make a really, really nice plug then pull a female mold, then start making parts.

I just finished a Tri-Pacer cowling that is 9" deep and around 18" around at the back.  I used blue foam, sanded it smooth after shaping and then applied two coats of Z-Poxy, sanding between coats.  Then I filled any little imperfections and applied two more coats of epoxy.  It made a really nice smooth buck/plug.  I used a plaster mold for the female mold, but screwed up on the release agent and had to destroy the mold to save the cowl.  But the male plug is great, ready for my second plane when this one is done.
Will

I think MDF would be far to heavy to move about at 1/5 scale!, even for a plug! I think an egg crate of cheap ply filled with foam will have to be the answer!

Cheers  Neville