Bonding the foam together.
How to glue silicone foam mat.
Spray a solvent based activator accelerator aa on either the silicone rubber or metal.
Since you are working with foam mats you can slice into the foam to give more contact area for the adhesive.
Silicone glue works best on silicone rubber.
So yes you can use liquid nails type adhesives but you will be better off with their general construction adhesive than the milder stuff designed for polystyrene.
Silicone can be glued but you often need a special surface activator chemical to prepare the silicone and the substrate to be bonded.
Rough the silicone rubber and the metal with a low grit coarse sand paper.
People like permabond and loctite can do them.
It is fairly easy to obtain at hardware or big box home improvement stores.
Warm the polypropylene surface with a hair dryer or heat gun.
Synthetic foam and silicone are good partners.
Applying glue to a small piece of foam place the two pieces of cushion foam that need to be glued on top of each other with the sides to be adhered facing outward as shown to the lower left.
To glue silicone rubber to metal.
Epoxy silicone vinyl caulk and many other glues and adhesives will work.