How to Make a Secret Accordion Card

write your letter or a secret message on a letter-sized sheet of paper

and fold in half, lengthwise...

and fold in half, again..

and again.

Fold together again, so that you have a thin strip of paper...

and draw lines like this.

and make a series of cuts alternately upwards and downwards. Let the cuts approach the edges but leave a piece of paper intact there.

ok..

Straighten the paper on a table. Make sure it doesn't get twisted. Unfold to get the original letter format. Straighten the folds with the side of your palm.

Take the letter by the top and bottom and stretch. You will get a net and the message will be impossible to read. If you put the letter back to its original shape, you will get a readable message again.