Foam matres ?

Where do you guys get foam for your beds? 

or t n ttt for short (tnttt.com)
https://www.tnttt.com/
Keith B wrote:however, I also heard someone bought 3-4 queen "toppers" at Wal-Mart, 3M spray glued them together, cut to fit and had a really comfy "mattress" for like less than $100.