Here is another idea from the Lancair crowd. Lay a piece of polyethylene sheet on a flat surface. a bit wider and longer than the fiberglass. Lay the glass on top of the plastic and pour on the resin. Spread to saturate the cloth and lay another piece of the Poly on top and squeegee as much of the resin out of the cloth as you can. Brush the styrophone very lightly with the resin using a brush. Remove the top poly sheet and using the bottom one as sort of a handle, carry it to the foam. Press the cloth to the foam and remove the final layer of polyethylene. Smooth with a gloved hand.
The image shows the technique for the horizontal strut fairings - very light.