Step 1: Cut Out the Frame of the Car

Start by cutting out a rectangular piece of cardboard. This piece is going to be the bottom of the construction where the motor and gearbox will be placed. You can decide the size of the bottom piece but some great measurements could be 20x10, 30x15 or 40x20. When you are done with the bottom plate, you are going to start with the “walls” of the construction. The important measurements of the walls is that they have to be as long as the bottom but you can decide the height by yourself. This was our measurements:

Step 2: Glue the Base Together

Glue the bottom piece and the “walls” together. When you have done that you should have a rectangular shaped box without a ceiling.

Step 3: Build the Gearbox

The motors that we had in our makerspace had about 14000 rpm which is way to fast for the droid. If you use a motor with such high rpm the droid may not work, and if it works the droid will be too fast and weak. To solve this problem we decided to build a “gearbox”. The gearbox is the solvation to make the droid a bit slower but more importantly stronger.

Building the gearbox: Start by taking all the materials you need, six gears, three with ten teeth and three with 50 teeth. You also need four sticks from popsicles and four sticks which will be used as axles. When you have all the materials put it together just like this:

Step 4: Create the Circuit

There’s two options to this step. If you want the droid to go backwards and forwards you will need to build a circuit similar to the first picture. although it can be simplified by only using 2 switches each connected to the + and - sides of the battery, as well as the dc-motor, This is called a H-bridge. This feature is not necessary and can be skipped. If you don’t feel the need for the reverse-feature, connect the battery to the motor and add a on/off switch. We made a H-bridge and the second and third picture is our circuit.

Step 5: Make the Wheels

Use a divider to make circles of cardboard at the desired size. The wheels needs to be high enough to stop the box from touching the ground. Use a box cutter to cut out the wheels. If you want to add more grip to the wheels, simply use either black electric tape or a thick rubber band and wrap it around the wheel, cut a hole in the middle of the wheel that’s big enough for the stick to fit through.

Step 6: Glue the Rest Together

Glue together the walls, the wheels, the gearbox and the motor.

Make sure there’s enough glue for the components / parts to not fall off.

Step 7: Decorations

To make the repair droid look like a repair droid you’ll need to make a removable roof. Make the roof look like the top off the mouse droid/repair droid. Our roof looks like this: