Futon frames come in many different types of materials. There is hardwood, pine, oak, rattan and tropical wood. Each of these woods comes in different colors and some are sturdier than others. There are also futon frames made of metal, which is much lighter and easier to handle than wood. In general, a metal frame is pretty sturdy. A futon frame may a bi-fold or a tri-fold futon frame. The bi-fold is the most common futon frame, where the futon mattress is folded in half the long way. The tri-fold frame is where the futon mattress is folded in thirds with the bottom third folding under the middle. These frames are great for small spaces because they fold up smaller. However, the futon mattress on a tri-fold is a lot thinner and it is harder to convert from a couch to a bed because you have to fold the mattress three times. Most people choose these frames if they plan on using the futon as a couch and less frequently as a bed.