Check [link=http://www.rcuniverse.com/forum/m_2830021/anchors_2910460/mpage_1/key_/anchor/tm.htm#2910460]THIS[/link] thread out. It contains details of the cowling plug construction for the fiber-lite 30% Edge 540. Some deviations from what I preached then to what I practice now:

1. I don't use aluminum templates between the layers of foam. The thermal expansion properties seem to be nowhere near foam, glass, or plywood. This creates a 'ghosting' effect...not noticeable on the final parts, but it will drive you insane when you see it on your finished plug. The slight (0.00005" or so) 'dip' that is created by the aluminum contracting is visible. You can sand it out, then it appears again. I'm pretty sure it's caused by the delta in the thermal expansion but I'm not 100% sure. Use lite ply...or even better (I JUST thought of this!!!) use 1/32" aircraft ply for the templates. The 1/32" aircraft ply cuts GREAT with scissors and would still serve as a decent sanding guide.

2. The 8.9 oz satin weave FG has fallen out of favor with me. The weave is very tight and does not release air very well. I use 3 layers of 3.2 crowsfoot cloth in it's place. Still a tight weave (no pinholes), but unbeatable conformability and great air release.

3. I tend to use wipe-on liquid mold releases (Frekote, Chemlease, Zyvax) instead of wax and the dreaded PVA. It took me years and $$$ in different sprayguns to get my PVA spraying technique down...what a waste. I don't use any 'sacrificial' releases now unless I absolutely have to.

-Tom