You can use any material you want to make your tangram set, the only requirement being that you can cut or form it in to the shapes. I've seen sets made of paper, cardboard, wood, ceramics, glass, mother of pearl and metal. Some beautiful examples from China were made of ivory with inlaid and carved ornamentation on the pieces and box.
Whatever material you choose to use, you will need a four inch (or a 12 cm.) square of it, usually about one eighth of an inch (two mm.) thick for a puzzle the size I like to make. You can scale these measurements up or down for bigger,smaller or thicker sets. Being able to divide the square into a four by four grid of squares is the important thing here.
To make a puzzle the 4 inch size I like to play with, draw a grid of 1 inch or, if using metric,3 cm squares directly on the material or on a paper pattern. You then mark off the blue cut lines as shown below.
Cut your material carefully along these blue lines. This will produce the seven tan pieces; five triangles, one square and one rhomboid. Take note that slicing rather than sawing will produce the best result. The wider the cuts, the more the pieces lose along one or more sides, making the piece not quite true. A knife, scissors or *thin* saw blade would work just fine for our purpose.
Smooth the pieces as needed and apply your choice of finish. I prefer black tans, but hey, it's your set, use what you like or none at all.
Jaime Jorge sent me an easy way to fold the cut lines of a tangram set. All you need is a sheet of paper and these pictorial instructions from him. Thanks a lot, Jaime!
Now that you have a set, jump to the puzzle page to try them out. Good luck with your puzzling, I know you'll have some fun with your new tans.