a vacuum forming mold has a plurality of dies with at least one die being movable with respect to the other dies . the die can be movable in a linear direction or they can be movable in both a linear and angular direction . a plurality of plastic sheets are heated and placed on a respective die with a vacuum being supplied through the dies to attract the plastic sheet . once formed , the dies are moved together to create a seam bond between adjacent pieces of plastic sheets . additional heating can be supplied to insure an adequate seam bond if required . in another embodiment , a single sheet of material composed of a plurality of sheets of material is used . the single sheet of material has a plurality of preseamed areas connecting each of the individual plastic sheets . these preseamed areas are positioned inbetween adjacent dies of the plurality of dies and the process continues as described above for the multiple sheets of material .