I kept that capsule (obtained from a Kinder Egg) in a scrap box for about four years ... until one day I figured it could be a perfect Minion body!

After making some sketches and the templates, started the work, which took me only one afternoon to make the body and one more afternoon to the electronics.

List of materials and components:

• Kinder egg capsule;
• high impact polystyrene piece;
• a pair of wheels (obtained from Nutella pots);
• third wheel (obtained from an old cassete player system);
• a pair of micro DC geared motors with hubs and brackets;
• small ball bearing with flange;
• screws and nuts;
• Arduino UNO (note on the picture of the materials and components that an Arduino Nano is shown... but I ended up using an UNO board);
• L298N breakout board;
• HC-SR04 sensor;
• a pair of LiPo batteries;
• jumper wires;
• thin wires (for the hair).

Tools and others:

• hand drill;
• metal ruler;
• scissors;
• sandpaper;
• pliers;
• utility knife;
• screwdriver;
• permanent marker (black and blue);
• glue stick;
• instant adhesive (cyanoacrylate ester);
• masking tape;
• soldering iron;
• solder wire;
• heatshrink.

Step 1: Making the Body

The whole process of making the body is better shown in the video below, but I'll describe it here.

I put the "eyes" (HC-SR04 sensor) template into place, and marked the circles with permanent marker.

With utility knife cut the circles to fit the sensor.

With masking tape I set the "elastic" of the goggles, and painted it with black permanent marker. I also painted his mouth.

With blue permanent marker I painted his clothes.

With glue stick put the template for the "T" bracket of the base on a piece of high impact polystyrene. With a 1mm drill I marked where will be some holes for screws and the small ball bearing later. With utility knife I cut the piece (with scissors on the rounded side), and with sandpaper I gave a better finish to the edges.

Joined the "T" bracket and the base of the capsule with instant adhesive (aligned the two parts with a screw in the middle of them, and removed it later - the screw). I sanded a bit before join the parts for better grip.

I put the hair (thin black wires) through a hole and glued it with instant adhesive.

With the templates of the wheels, made the holes.

Step 2: Electronics

The electronics is quite simple, as follows:

HC-SR04 sensor

• VCC >> 5V
• Trig >> Arduino pin 10
• Echo >> Arduino pin 9
• GND >> GND

L298N

• ENA >> Arduino pin 3
• IN1 >> Arduino pin 4
• IN2 >> Arduino pin 5
• ENB >> Arduino pin 6
• IN3 >> Arduino pin 7
• IN4 >> Arduino pin 8

The LiPo batteries are connected in series (so 7.4V) and his positive passes through a switch and goes to the 12V connector of the L298N. The L298N have a 5V connector, which provides the power to the Arduino board (in the 5V pin). Arduino and L298N must have a common GND.

The only necessary soldering was to connect wires to the motors.