Wire, headers, breadboards, switches, LEDs, speakers, motors, batteries and the mechanical hardware that holds everything together. Sold as individual parts or small packs, so you can stock up on the things you use regularly.
Starting a parts drawer
If you're new to electronics, the Maker Essentials packs cover some of the basics: mini breadboards and jumper wires, headers, switches and potentiometers, and micro motors with wheels. Add a breadboard, some Jumper Jerky and a set of crocodile leads and you've got the basics for experimenting without soldering.
For more permanent builds, wire spools, headers, an Adafruit Perma-Proto board and a screw, nut and spacer set are useful additions. The Tools department has the cutters, pliers and solder to go with them.
Lights, sound and movement
For lighting, there are addressable RGB LED strips compatible with NeoPixel and DotStar projects, LED noodles, LED filaments and packs of 3mm LEDs. For sound, you'll find mini speakers and buzzers. For movement, there are LEGO-compatible servos, Mecanum wheels, motor brackets and a submersible pump.
Power options include LiPo and lithium-ion battery packs in different capacities, along with USB, DC and solar chargers. For inputs, there are tactile switches, arcade buttons, a joystick and mechanical keyboard switches with matching keycaps.