What you need
The printed template
Card
A craft knife and a cutting mat
A ruler
An adult for the cutting
How to build it
Print two copiesOne to cut, one for your friend. They must be identical or it will not work.
Stick to cardGlue the template flat onto card and let it dry, or the windows will tear.
Cut out the seven dashed squaresAn adult holds the knife. Cut against the ruler and take your time.
Write the secret firstLay the grille on paper, and write one word of your message in each window.
Lift the grille offNow fill in all the space around those words with an ordinary, boring letter.
Send the letter onlyYour friend lays their grille on top, and only your words show through.
Mark a corner of both grilles with a dot. Laid down the wrong way round, the windows land in the wrong places and the message is gibberish.
The template
Print this at 100 per cent, not fit to page, or the sizes will be wrong. The ruler line below tells you whether it printed correctly.
The bar above should measure exactly 10 centimetres. If it does not, your printer has shrunk the page.
Now send something
Hide GO TO THE OLD OAK AT SIX. The hardest part is writing a dull enough letter around it, which is exactly the skill.
Hidden in Plain SightBack to MakeRead more elsewhere
Longer, harder and written for grown-ups. Worth a look when this page runs out.