Introduction: Scavenger Hunt

My kid and his friends are really into dinosaurs. So as a birthday activity I created a Dino-themed scavenger hunt.
There were 8 participants and everyone got a mini-clipboard with a unique color/shape combination. After finding all hints they each had a unique set of dinosaur features (e.g. two-legged meat-eater with horns). They then had to use their dinosaur knowledge to find the correct dino from a lineup before getting a trophy.

This is not a step-by-step instructable. Instead it is a collection of ideas which you will have to adapt based on what materials you have available. The theme can easily be adjusted to make it a hunt for pirates, comic book villains, etc.

I will be explaining most of the components below. The high-level game flow is this: find envelope with rattlesnake prank, find locked chest with hint for key, find key and unlock chest. Get first clue in chest, along with magnifying glass, and hint to search for silver lantern (green camera). The lantern contains the second clue and points them to the yellow Dinopad. Using the magnifying glass the Dinopad instructs them to search for binoculars. The binoculars allow decoding of the Dinopad resulting in the third and final clue. After that each kid got to pick their matching dinosaur out of the lineup.

Step 1: Components

Rattlesnakes - The first hint ("find the wooden chest") came in a small envelope labelled "Dino Eggs - Keep refrigerated to prevent hatching". The envelope contained a special surprise, commonly known as rattlesnake prank: Take a large paperclip and bend it into a V-shape. Take a button and thread a rubber band through it, connecting it to the edges of the paper clip. Now wind up the button by spinning it as much as possible before carefully inserting it in the envelope. When the envelope is opened this will make a loud rattling sound.

Key - My previous project was building a treasure chest and that got reused for this scavenger hunt. The important part is that the latch is large enough for a padlock and the box can hold a few items. The padlock key was stuck inside a puzzle box (not shown here). The kids first had to find the puzzle box (guarded by a T-Rex), then extract the key, and finally use it to unlock the chest.

Camera - this is a cheap toy camera (thank you Happy Meal!) that contains a number of microfiche images behind the viewfinder. I disassembled the camera, removing the image reel and shutter button. I laser printed a hint on a transparency ("Find the silver lantern!") using a small font (4 pt) and then hot glued it behind the viewfinder before putting the camera back together. One tricky part is that the focal range of the lens is extremely narrow and the transparency has to be glued in just the right spot to be readable.

Lantern - this AA powered LED lantern was available at my local dollar store for $3. The design is pretty good - featuring an inner cylinder that telescopes out of the silver body. I printed out the clue on plain copy paper and put it between the lights and the plastic diffuser. As a side note: please do not buy the wall-powered version of this lantern; it is a known safety hazard.

Dinopad - I have had the most fun with this prop. Typical remote controls emit high powered infrared light when a button is pressed. I took an old remote and soldered leads to one of the buttons. Those wires are connected to the toggle switch you see on top. The sole purpose of that is to have an IR light shine constantly without having to hold down a button. The remote was hot glued into an oversized hollow clipboard with the light pointing up at the bottom left corner. Now you might ask, “how does this help since infrared light is invisible to the human eye?” This leads us to the “dinoculars”.

Dinoculars - all digital cameras can record infrared light. High end cameras will have high quality filters to block IR light. Fortunately I had a cheap Android phone with a cheap filter on hand. After confirming that the camera was able to record IR light, I placed it inside a Google Cardboard VR enclosure. I tried a couple of different free AR applications. The only one that worked well is Zeiss VR One. It has a pass-through mode so you get a pseudo-3D view of the phone’s camera. Putting it all together you end up with something that works like binoculars but allows you to see infrared light (which shows up as bright purple on screen). The kids eventually figured out that by looking at the clipboard with this contraption the bottom indicator is visible and that the bottom row contains the final clue.