Having a little trouble finding actual "memory foam". I can find the mattresses, but not just the foam---but I'm going to keep looking. The folks at the Original Mattress Factory in Raleigh make custom mattresses, so I"m also getting a quote from them. Thanks all, for your help with this! Another thing I have learned in this venture is that not all "outdoor" fabrics are necessarily more durable than regular upholstery fabric. Some outdoor fabric (such as that used for chair cushions, etc.) is only rated 6000 "rubs" or "light domestic" use. The most durable fabric will be rated 50-60,000 rubs, but we probably don't need to get that crazy! I think Sunbrella is 40,000 rubs, or double-rubs (whatever that means!).