(4) Assembly. The assembly of the pieces can be permanent or temporary. If the model is bulky and must be moved frequently, it is preferable to have a temporary assembly where the pieces hold together with toothpicks for Styrofoam or pins for Foamcore. For a strong and permanent model, liquid white glue is ideal for porous and absorbent materials like foam and cardboard.

You can use a spatula to spread the glue on wide surfaces and you must always apply pressure while drying to avoid air pockets.
+Advice:
*Some adhesives can damage surfaces. Strong glue can melt Styrofoam and tape can tear Foamcore.
*Foamcore can be bent to form angles by making an incision in one of the cardboard surfaces which reduces considerably the work of assembly.

(5) Finishing. During the finish, you must prepare the surface of the material. At this point you can apply paint to cover imperfections or to add color or texture. A base coat is necessary for porous or colored Styrofoam but a single coat is sufficient for Foamcore.

For Styrofoam, latex paint as a good adhesion but is costly while for Foamcore many types of paint work well such as acrylic paint which is more affordable.
+Advice:
*To even porous surfaces or fill holes and cracks, silicone is ideal and some types can be painted.
*You can even dense materials with sand paper and a sanding bloc, especially for joints.
*You can sand Styrofoam lightly to increase the adhesion of paint.
*To hide exposed foam surfaces (Foamcore), you can stick cardboard strips.

Here are three model projects including the plans and the measurements according to three levels of difficulty. You can build a ballcourt, a pyramid-temple or a palace by choosing your materials and finishing. Printable version in PDF format
Note: If you are not familiar with the metric system, you can convert the centimeters (cm) in inches by dividing the measurements by 2,5.