Folding Futon Pads make convenient folding guest beds.
Folding Futon Pads also make cute bedroom furniture for children. Available in both tri-fold and bi-fold construction, they store easily under a bed or in a closet.  A folding futon pad cushion can be ordered in varying thickness and are available with cotton fabric in various colors.  The foam in these are a guest-bed grade and won't last as long as a futon mattress, so you may want to upgrade to a true futon if you plan frequent or heavy use.