Have some on the way from vintagepartsgirl Lozza, the thickness stated was .35 mm, would that be right for fibreglass reeds?
The eBay seller vintagepartsgirl has a lot of gaskets & reeds for period reed valves, I bought spares for my G.E.M 6V from them & the reeds have basic dimensions to help you pick the correct set.
What would be your suggestion for material, I will try the petals on block when they arrive to make sure they are the right size & send you a set to copy if you think material or thickness is wrong