The holder for 4 AA R6 batteries is an ideal solution for people who need a simple and reliable way to connect AA batteries to obtain a voltage of 6 V

3-AAA Battery Holder

Rechargeable NiMH AA Battery: 1.2 V, 2200 mAh, 1 cell

The Step-Up Buck Voltage Regulator module with adjustable output voltage in range of 4-25V with a input voltage range of 1.5-16V and a maximum output current of 2A. Pololu 799

Pololu Low-Voltage Dual Serial Motor Controller

Tamiya 70168 Double Gearbox Kit

Brushed DC motor in a housing 130 supplied with a voltage ranging from 3 to 12 V, with a rotational speed of 11500 RPM and a current consumption of up to 800 mA. Pololu 1117

Tamiya double gear dedicated to small mobile robots. It is made of plastic modes that can be adjusted to two gears: 58:1 and 203:1. Pololu 61

Tamiya 70157 Universal Plate Set (2pcs.)

Tamiya 70167 Single Gearbox (4-Speed) Kit

Tamiya 70093 3-Speed Crank-Axle Gearbox Kit