Figure 4 Deadfall Trap is probably the simplest trap you can build in the wilderness. It only requires three sticks and a weight (and some bait, maybe). See this link.

This 3D-printable version of the mechanism is great for educational purposes, demonstrating the types of notches that need to be carved into wooden sticks for the trap to work properly. You can even print this miniature model to carry with you as a reference next time you head out to the woods to practice building the trap!

The Pole v2 and Trigger v2 parts make the trap much more sensitive to trigger.

Start by setting up the post. Then, place the lever and rest the weight against it, allowing the lever to apply pressure against the trigger, which you will set last. It’s much more difficult if you try to hold the mechanism together and place the weight on top afterward. Keep in mind that 3D-printed plastic parts can be slippery, which adds an extra challenge. You might want to put a small piece of adhesive putty at the end of the lever where the weight rests to help keep it in place.

The easiest way to get familiar with setting the trap is by using a rubber band as the "weight", along with the included stand to support the trap so it can stand on its own.

When set with a rubber band, you can also use multiple traps to create fun chain reactions. For this purpose, the set includes a "helper" piece that attaches to the front of the trigger, so it can trigger another trap in the chain. But be warned: when the trap is triggered, it launches projectiles into the air, especially if you use a strong rubber band. Make sure no one is too close to the trap when it fires!

If you want to use this just as a chain reaction toy, consider the safer, jointed version.