Super Bot Gears - a 3D-printed Arduino starter kit

Hello!
This is an educational Arduino set I've prepared for my nieces to teach them about electronics. While I was at it - I decided to also make it Open Source and publish it on the internet for free!

The wiring diagrams, Arduino Code, instructions and the box label can be found on my Arduino project hub:
https://create.arduino.cc/projecthub/bzqp/super-bot-gears-a-3d-printed-arduino-starter-kit-91485e

Printing
No supports needed. The beams are printed vertically, so make sure your printer can make consistant layers or your beams may break.

The holes may require pre-drilling or sanding depending on your 3D printer tolerances.
These small servos always seem to have a slight difference in dimensions depending on the manufacturer so be aware of that.

Needed parts (and approximate price):

- 19 3D printed plastic elements (0-10usd)
- 3x M3 washers (0, 5usd)
- 1x M3 14mm bolt (0, 5usd)
- 4x M3 12mm bolt (0, 5usd)
- 6x 8mm bolt + 3x 4mm bolt (sold with servos)
- 3x SG90 mini servo (4, 5usd)
- Dupont-style jumper wires, male-male, female-male (5usd)
- Arduino nano compatible board (2usd)
- 10kOhm potentiometer (0, 5usd)
- 220 Ohm resistors (0, 5usd)
- 6800 Ohm - 10 kOhm resistors (0, 5usd)- 5V LED (0, 5usd)
- 4x 10-20 kOhm photoresistors (1usd)
- 1x HW-504 joystick (2usd)
- 5V powers supply unit or a 5V 450mA phone charger (2usd)
- 1x 400 points solderless breadboard (2usd)
- 1x USB cable (1usd)
- 1x small screwdriver (1usd)
- empty cardboard box - optional (0usd)

The instructions (together with some interesting mechatronic facts) are available in English and in Polish. 
The license allows any use (including commercial if you wish so). Just remember to attribute the author. :)