The title is taking license with the real phrase, “necessity is the mother of invention.” We are not big on guests and frankly have turned our guest room into an office/studio. But recently we had a visitor to stay a couple of nights and the only thing we have resembling a bed is a single size air mattress. The guest is not a nimble young person, and I knew I needed to get the mattress off the floor a bit. My imagination went into overdrive.