I taped these together. Lay the tape out in a straight line upside down. Flip the rubber inside out & roll along. pinch each side flat & I give it about three layers and try to keep it level and always pinch it down flat. then foam - I usually cut some away to compensate for the tape layers.Before I glue I like to fit it in and roll it to catch any weirdness. I don't have a balance machine so I have to use my head - so I roll them. If they go in a straight line - glue em up.