Knex Rubber Band Car

This car is a simple-build knex car that uses a rubber band as its force to move it forward.

Step 1: Gather Your Materials

For all of the materials, you will need four grey rods, one yellow rod, four knex wheels (two small and two large), one rubber band, four yellow semicircle connectors, three dark grey or red corner connectors, twelve grey loop single connectors, and two tan single connectors (with a protrusion).

Step 2: Building the Frame

Start with two grey rods. Connect all four yellow connectors at a perpendicular angle to the rods. Then, take the other two rods and put them through the holes on the yellow connectors, leaving an inch on either side so that the wheels can be put on later.

Step 3: Putting the Wheels On

Take 8 grey connectors, and all four wheels. Put a grey connector on either side of the yellow connectors so that they are snug against each side of them in order to keep them stationary. Then, place your two big wheels on with the side of the wheel that has a little extra hole in it facing out. Do the same with the little wheels to create the front axis.

Step 4: Securing the Wheels in Place

Add the two tan connectors to the rear axle with the big wheels and insert the protrusion into the hole in the wheel. Then, add two grey single connectors to the front axle on the outside of the smaller wheels.

Step 5: Adding the Pulling Force

First, grab the three dark grey connectors, the yellow rod, the rubber band, and two single grey connectors. Put the rubber band around the rod and connect the connectors at the ends of the rod. Then, snap them onto the middle of the two grey rods (NOT the axles). Then, take the grey single connectors and connect them on the grey rod on the side of it closer to the rear axle but right against the dark grey connectors (so the yellow rod is held in place). Then, in order to make the car move, put the final dark grey corner connector and snap it on the center of the rear axle. Wrap the rubber band around one of the notches made for a rod to go in it in order to create tension and let it go!