clyons you could use foam [builders] and f/glass --- acetone will remove the foam --bit of goo mess ---you can mould the foam once dry --- check out the old fiat 500 with bike engine on you tube --complete build. this is more or less the way racetech done his and his mate used vw arches.I also used foam[lots of dust]but was in too much of a hurry.I was thinking of the subaru style.cut arch [like bridge] another flat sheet cut out semi for wheel.check a few Banzai or japanese - motor mags all about jap cars