The commercial modular boards can be very expensive. The DIY designs I've seen are for large boards that need to be stored behind the couch and are not easily portable.
This design is modular and portable. The board breaks down into 2ft x 2ft (about 600mm x 600mm) sections and easily clips together when you want to play. You just need a table or floor space to put the board on.
There are a few things I could of done better, but at least you can learn from my mistakes :)
Step 1: Materials and Tools
EVA Floor mats - Bought a pack of 6 from Kmart ($AUD 28) The ones I got were 620mm square.
Styrene Plastic Sheet - 1mm thick styrene plastic sheet also known as plasticard. This usually comes in large sheets from plastic suppliers. They can usually cut it to size for you. I actually used 2mm thick but was not necessary. It also cost more. Mine was black but white would of been better. ($AUD 70 for 2mm thick, 1mm thick would be about half price)
Spray-on Contact Adhesive - I used 3M 80 Neoprene Contact Adhesive ($AUD 32 for a can) which is a bit expensive. You could use any contact adhesive that is solvent based. It should slightly disolve the surface of the styrene and stick well to the EVA foam. I was able to test the adhesive with some scrap styrene and some EVA holes that hadn't detached from a tile.
Spray Paint - Auto Primer Spray Cans (Grey and Tan)
Methylated Spirit- (Denatured alcohol) for cleaning plastic before gluing.
Metal ruler - 600mm or 1 meter metal ruler (or 1 yard metal ruler)
Very sharp knife - box cutter or utility knife
Clamps - ratchet or locking clamps, though G clamps can be used.
Straight Edges - aluminium angle, square tube, or straight lengths of wood.
Engineers Scriber or Fine Permanent Marker - for marking out the styrene for cutting. Scriber for black plastic (or a white wax pencil). Fine marker for white plastic.
Sandpaper - medium grit say 300 to 600
Tape - masking tape, packing tape or wide plastic tape
Newspaper or a drop cloth - lots of it, to stop glue landing on things it shouldn't.
Face mask - to stop you breathing in glue and paint.