The last thing we have to do now is to add our LEDs into our printed t-shirt design. Turn your printed t-shirt inside out, and then take your piece of fabric with your LEDs stitched into it and place it on top of the design of the t-shirt with the LEDs facing the t-shirt. Take some time to ensure that the two designs line up nicely and pin it in place. I then folded the fabric back over the back of the LED stitching so that none of the conductive thread would come into contact with the wearer's skin. With everything pinned in place, sew three sides of the design onto the t-shirt. I used a sewing machine to do this, but you could do it by hand if you do not have access to a sewing machine. Be sure to leave the side of the design closest to where your cables attach to the poppers open so that you can attach and detach the Pi Zero from your...