That would be a very good idea. You could also try this: Sew 2 small squares together like you would if you were making a pillow (felt works well for this). Leave 1 side open and turn to the right side. Tuck about 1/4 of the open side over so you won't have raw edges for the next step. Starting at the open side, sew a curvy line throughout the square. Move over about 7/8 inch or so and sew another curvy line following the path of the line you just sewed. Basically, you are making a track. You can make it as simple or complex as you want. The track should start and end at the open side. Drop a marble into the track. Topstitch the open side closed. Now you have a small "fidget" for your stepson to take with him. To use it, he just moves the marble back and forth along the track. I have seen this work well with many of the autistic kids I work with.