For this photo, I had the exposure on the camera set to 13 seconds. When I pressed the shutter release button, a light flash was used to show the subject and the subject proceeded to use a blue light stick to write their name in the air. When the shutter closed, their name became visible in the final image.
For this photo, I had the shutter speed set to 20 seconds. I pressed the shutter button, grabbed the flash and lit my subject, then I rushed to grab the blue light stick and quickly but carefully moved the light going around their arms. When the shutter closed soon after, the image came out just as I expected it to look.