Kits or Sets
Tangram games can be purchased in kits approved for different age groups. Choices include magnetized, wood and plastic versions. For younger children, keep in mind the size of the shapes as well as sharp angles for safety reasons. Prices depend on the kind of set you choose. For instance, lesser-expensive versions may not come with containers. Higher-end versions made out of handcrafted wood or stone make for nice gifts.
Homemade
Choose a material you wish to use for the tangram set. Paper, cardboard, felt, wood or acrylic all make good choices for a tangram game. Cardboard is a sturdy choice that can be cut up quickly. Templates for creating the shapes can be found online. Cut the shapes from a template and create a concise rendition of a tangram set. You can let the kids color the different shapes. Solid colors are better suited to tangrams as the set will be used to create many different pictures.
Online
There are many websites offering tangram games. Search for titles created for kids to find an appropriate skill set of games. Choosing a game within the child's skill set will prevent undue frustration. The websites often allow kids to choose the difficulty of the puzzles, allowing children to progress through the puzzles as they get better at the game.