One of our most successful projects this semester was making T-Shirt Light Up Bracelets! We pre-cut rectangles of cloth from different colored t-shirts and gave students the option of picking their favorite color.
The students then sewed a simple straight line to make the rectangle into a tube. (Some of them stopped after this point and simply made an arm sleeve with no bulb or battery.) Then they took a battery and an LED bulb of their color choice and put the battery inside the tube and poked the LED wires through the fabric. To create an on/off button, the sleeve was turned inside-out and double-sided tape was positioned in such a way that the wire would only touch the battery when pressed!
Finally, the kids measured the bracelet around their wrist and made one more sewing line. We could imagine this with hand-sewing as well, but it was an extremely easy introduction to the sewing machine for many of the students!