Thick plain sheet
Design of your choice
Draw the design of your choice on the sheet and colour them. Measure the size to draw gridlines in the back of the design to get equal squares..for smaller kids make it into lesser pieces. Now draw the shape as to fix the pieces-atleast 2 on each piece. Cut them neatly.
Use wide cellotape to cover the pieces..this way the kids wont be able to tear it off.