Glueing EPDM Rubber at Temperature / Water

Hi there, Can someone please help me with a problem I am having. I have a rubber U shaped extrusion approx 12mm x 2mm gap x 4mm rubber
thickness. It is easy to obtain in EPDM, but I could probably get it in Neoprene. It is sponge rubber.
I am trying to glue this extrusion into a circle to make a gasket. The circle has a diameter of 200mm.
I have tried cyano (works great, but cant handle the 100C temperature and 20% ethanol / water mixture) I have tried epoxy (doesnt stick) I have tried several contact glues (They fall apart after a short time) I have tried Rema Tip-Top SC4000 which is the best so far, but it still seems to slowly fall apart. I have tried all this on EPDM sponge - would the SC4000 work a lot better on Neoprene sponge?
I would prefer to have it vulcanised, but it seems no-one wants to do it because it requires a mould.
Can someone help me work out how to do this? I need to do several hundred. I am located in Geelong (near Melbourne) Australia.
Any other groups I can post to? Thanks a million. Greg
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