How to make real spy gadgets

Updated July 19, 2017

Becoming a spy takes cunning, stealth, and of course, cool gadgets. But there is no need to spend money when you can make your own spy gear at home. Using common items you can find around your house, you can create secret messages and build tools that allow you to observe the actions of others while you remain in the shadows. With these gadgets, you'll be on your way to becoming a super sleuth in no time.

Mix together 2 tbsp water and 2 tbsp baking soda in a small squeeze bottle with a pointed tip.

Use your mixture to write a secret message on paper using the tip as a pen.

Allow to dry completely. Message will become invisible as it dries.

Place grape juice concentrate in another small squeeze bottle.

Squeeze grape juice over paper and use paint brush to spread it over entire surface. The acid in the grape juice will react with the baking soda, causing the secret message to reappear.

Place a marble in middle of construction paper.

Roll the construction paper tightly around the marble so that the paper forms a long tube around the marble.

Tape the paper in place to secure your tube.

Poke the marble down to one end using a pencil so that half of the marble is poking out of one end of the tube.

Put the end of the tube with the marble up to a keyhole and look into other end. You will be able to see around the room, though everything you see will be upside down because of the way the marble reflects the light.

Open the ends of each milk or juice carton and tape them together so that you have one long tube.

Cut a square in the bottom on the front side of your tube. The opening should be about 2 inches by 2 inches. Cut the same size opening at the top of the backside of your tube.

Put the cartons aside. Hold your two mirrors, one above the other, adjusting the angles you are holding them at until you can see in one and out the other. It helps if you try to see over an object, like a counter. Hold one mirror at eye level and the other over the top of the counter top. When you can see over the counter in the bottom mirror, you know you have the right angles.

Insert the mirrors into your periscope at the angles determined. Cut two diagonal slots in your tube, one at the bottom and one at the top, that match the angles of the mirrors and allows the mirrors to be seen through the holes you cut out earlier. Slide mirrors in place and secure with tape.

Look through the bottom window. You should be able to to see out the top of your periscope. If not, adjust your mirrors until you can. Now you will be able to see around corners and over counter tops without being detected.


Make a small pouch or decorate a plastic container to hold your invisible ink kit.


Get parental supervision before using sharp objects. Remember that grape juice can stain clothing and fabric so handle carefully.

Things You'll Need

  • Baking soda
  • 2 small squeeze bottles
  • Paper
  • Grape juice concentrate
  • Paint brush
  • Small clear marble
  • Black construction paper
  • Tape
  • Scissors
  • 1/2-gallon milk or juice cartons, rinsed and dried (2)
  • 2 small mirrors
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About the Author

Jamie Malone has always been passionate about writing and decided to pursue the craft professionally in 2009. She was published in the 2010 and 2011 "O' Cat Literary Magazine." She is a Magna Cum Laude graduate of California State University, San Marcos as a literature and writing major.