Sometimes the model pieces can be punched out. More frequently the printed parts must be cut out. Edges may be scored to aid folding. The parts are usually glued together with polyvinyl acetate glue ("white glue", "PVA"). In this kind of modeling, the sections are usually pre-painted, so there is no need to paint the model after completion. Some enthusiasts may enhance the model by painting and detailing. Due to the nature of the paper medium, the model may be sealed with varnish or filled with spray foam to last longer. Some enthusiasts also use papercrafts or perdurable to do life-sized props starting by making the craft, covering it with resin and painting them. Some also use photo paper and laminate them by heat, thus preventing the printed side from color wearing out, beyond the improved realistic effect on certain kinds of models (ships, cars, buses, trains, etc.). Paper crafts can be used as references to do props with other materials too.