Tools and materials:
1 yard neon elastic (check Etsy for some great choices, like this)
Interlocking belt buckle
Super glue, like E6000
Clips to hold elastic
Cut elastic to fit your waist when stretched, plus a few extra inches on each end.
Slide one half of the belt buckle a few inches down one end of the elastic. Add glue, and fold over elastic onto itself and the glue.
Repeat on other side. Hold in place with clips, and let dry.
Hopefully the belt is bright enough to take attention away from my lobster-red sunburn.