Width x Length
Due to their low thermal conductivity, polystyrene rigid foam sheets are used extensively as insulation in the building trades. Just as in the case with its “mother” polystyrene, the foam has also come to be used in model making. Fine and medium pored solid foam made from extruded polystyrene has become the most used material, especially so in the case of architectural models, Above all else, this is because it can be so easily and precisely shaped and formed with a thermic saw.
A thermic saw or the Styrofix are the best tools for cutting PS solid foam but one can also use a cutter if careful to hold the blade very flat when cutting through the material. If you prefer using a saw, band saws and circular saws having blades without opposing teeth are the most suitable. Still another possibility is to do your cutting with a lathe. Uneven or damaged surfaces can easily be made smooth by applying dispersion- or gypsum- or cellulose-based spackle. Edges can be rounded off and mistakes remedied by using (wet) sandpaper(< 180 grain).
For glueing smaller pieces together it is best to use Tesa all-purpose glue or UHU por contact glue. If you want try other glues it is best to make a preliminary test beacause PS foam can react badly to certain solvents. The glue should be applied on one side of the foam and both pieces should be then pressed together and separated again. After waiting a few seconds to allow for aerating, the pieces will - as long as the glue is still tacky - then stick to each other permanently. For glueing larger surfaces it is best to utilize a polysryrene compatible spray adhesive or polysterene foam glue. It should be noted that double-sided adhesive film can also be successfully utilized.
The colouring materials best suitable for colouring the foam run the gamit from acrylic or dispersion dyes, PLAKA colours , toning pigments as well as all polystyrene compatible paints (always make a preliminary test!). For spray painting one should use either the Marabu or Aerodecor sprays - unless you have an airbrush, which would be of course best of all. You must, however, be somewhat careful when using the spray paints: always spray from a distance of at least 25 to 30 cm and apply many thing layers of paint instead of trying to colour all at once (here too the best rule is Always Test First!)
Light blue polystyrene solid foam can be better spray painted white when as a first step it is spray painted grey.