Here is a fun version of a mouse trap car made with K'nex. You will need a wooden mouse trap with the hold-down/latch bar and catch removed. You will also need the K'nex parts shown in the supplies photo below. One of the red rods (the throw rod) has a 12" string tied to the top of it. An 8" length of solid hookup wire will be used to secure this rod to the mouse trap. You will also need a small amount of packing tape (not shown).

Supplies

Step 1: Build Chassis

Assemble the chassis as shown in the photos. Two connector clips are mounted at an angle on the blue rods and will be used to secure the mouse trap to the chassis.

Step 2: Seat and Secure the Mouse Trap

Install the mouse trap as shown. Use the two red rods to secure the trap to the chassis. Notice that one of the rod is installed underneath the hammer.

Step 3: Front Wheel Assembly

Build the front wheel assembly which will be attached to the front of the chassis.

Step 4: Rear Wheel Assembly

Build the rear wheel assembly as shown.

Step 5: Attach Wheels to Chassis

Snap both the rear wheel assembly and front wheel assembly into place on the chassis.

Step 6: Secure the Throw Rod to the Mouse Trap

Using first packing tape and then the solid hookup wire, secure the throw rod to the hammer of the mouse trap as shown. Notice that both the hammer and attached throw arm rest on top of the front red rod that is securing the mouse trap to the chassis.

Step 7: DONE Building, Ready to Test

Wind the string onto the rod connecting the rear wheels (very much like a string top) as shown in the video at the top of this instructable while gently pulling the hammer and throw rod back to the rear of the vehicle. While holding the hammer down, place the K'nex vehicle on the ground, release the hammer and watch it go. I hope you have fun building this model.