Secret Message Poster

Cool Science, Quick Crafts


we love this *spy* inspired poster for its clever use of color to reveal a secret code!

30 minutes

maker checklist

  • poster board
  • markers
  • scratch paper
  • red acetate gel (or DIY!)
  • magnifying template
  • scissors + glue


make your spy-glass


sketch a simple spy glass on heavy paper and cut it out. cut out the inside too!


cut a circle of red acetate to fit the opening for the “glass” in your spy glass!

or try this!

use clear acetate or plastic film (like the clear panel from a pasta box!) and color it evenly with a red sharpie. voila! once you’ve created your red filter, cut it to shape.

make your poster!


test your markers to see which colors are visible with your acetate and which ones are not. just make some marks on a piece of white paper, and lay the acetate on top of it.


the red acetate cancels out the warm colors, leaving cool colors visible.


write your message with the marker color that stays visible. leave lots of spaces between your letters.


fill the spaces with random letters in the colors that disappear.


hang the spy-glass from your poster by a string, so friends can discover your secret message!