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Rotating grille

A card with nine windows that turns four times and fills every square.

about 35 minutes the hardest one here makes a working machine

What you need

The printed template
Card
A craft knife, ruler and cutting mat
A pencil
An adult for the cutting

How to build it

Cut out the nine windowsAn adult holds the knife. Mark the dot corner clearly on both sides of the card.
Lay it on paper, dot at the top leftWrite the first nine letters of your message, one in each window.
Turn the card a quarter turnDot now at the top right. Nine new windows appear over nine empty squares.
Write the next nineThen turn again, and again, until you have gone all the way round.
Lift the card offThirty-six letters, no gaps, no order anybody can see.
Fill any spare squares with nullsIf your message is short, put in letters that mean nothing.
The windows have to be chosen so that four turns cover every square exactly once. Cut only the dashed ones on this template, or it will not work.

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.

10 cmcut out the nine dashed squares. the dot marks the top corner
The bar above should measure exactly 10 centimetres. If it does not, your printer has shrunk the page.

Now send something

Hide THE PARCEL IS IN THE SHED BEHIND THE OLD GREEN DOOR, which is exactly thirty-six letters if you drop the spaces.

Route with nullsBack to Make

Read more elsewhere

Longer, harder and written for grown-ups. Worth a look when this page runs out.

Grilles