This project was born from the desire to host STEM, especially eletronics and robotics classes for low income students in poverty-stricken neighbourhoods in Rio de Janeiro, Brazil. To make this project viable, we needed to keep the course material cost as low as possible. In order to achieve this the board was designed arround the ATiny85 MCU, a L293D and a 74HC595 shift register. The L293D allows us to control 2 DC motors, changing the rotation direction, however we can't choose the speed in whic they run. The 74HC595 gives us the possibility to interface the MCU with the outside world through 8 extra digital output pins. If we outsource the components from China the boards could be assembled for less than 4 USD, using through hole components allows the boards to be assembled in-house.
The small size and price also makes this platform a great choice for swarm robotics projects.