I have no affiliation with the vendors selling these parts, and can't promise functionality or support. These are just parts I've found useful when making small RCM controlled robots.

• Motors
  • TT motor with encoder how to wire
    • https://category.yahboom.net/products/encoder-tt-motor
    • TT shaped motor, with a quadrature magnetic encoder
  • "TT motor"
    • https://www.adafruit.com/product/3777
    • https://www.amazon.com/s?k=tt+motor
    • the classic yellow gearmotor, great for drivetrains
• Servos
• 5AA Battery holder
  • https://www.amazon.com/s?k=5AA+battery+holder
  • Use with NiMH batteries
• Wires
  • JST RCY battery wires
    • https://www.amazon.com/dp/B00Z04QFN2/
  • Qwiic cables (I2C)
    • https://www.adafruit.com/product/4399
    • https://www.sparkfun.com/products/17259
    • https://www.amazon.com/s?k=jst+sh+4pin+connectors
• Sensors
  • Proximity
    • IR proximity sensor
      • https://www.amazon.com/s?k=ir+infrared+obstacle+avoidance+sensor+module
      • digital, approx 1cm (1/2") range, can be used to detect if a gamepiece has been captured
  • IMU
  • Barometer/Altimeter