You should check your private messages PMs.
I purchased a 1/4" thick by 24" wide by 30" long piece of polypropylene ( resin doesn't stick to it ) from Tap plastics inc. I've been making sheets of fiberglass. I used 3/4 oz. fiberglass mat (1 layer only). The finished sheet is very flexible & can be cut with a pair of scissors. I can place it over a gap ( it's transparent) and mark the area to be cut out. The cut out piece is extremely accurate.

Do you have shackles on the front of the leaf springs?



