Funky foam can be used for block printing. It is easy to cut out and stick down and it can also be put through a hole punch to make small circles as part of the block. PVA glue is used to stick the pieces down. Fabric dye can be rolled on or a stencil brush used to apply different colours to the block.
Polystyrene sheets can be used to print with by indenting them with a needle or biro. These don't work as well with the fabric dyes - they are much better using printing inks.
Funky foam can be cut on a laser cutter to make much more even and intricate designs. This can then be stuck down on card and printed with.
The easiest way to screen print is to use a stencil beneath the screen. This is only really suitable for simple images as anything more elaborate will take a long time to cut out. If you do have a more elaborate design then you can use photo emulsion to prepare a screen.