One person who has likely fielded just about every curveball the kit business can throw is Adafruit Industries founder Limor Fried. Thankfully, she’s taken the time to post a variety of helpful kit-biz resources, materials, and suppliers over at LadyAda.net – plus there’s a discussion forum dedicated to the topic on Adafruit’s site.
Make a robot friend with Adafruit’s CRICKIT – A Creative Robotics & Interactive Construction Kit. It’s an add-on to our popular Circuit Playground Express, FEATHER and other platforms to make and program robots with CircuitPython, MakeCode, and Arduino. Start controlling motors, servos, solenoids. You also get signal pins, capacitive touch sensors, a NeoPixel driver and amplified speaker output. It complements & extends your boards so you can still use all the goodies on the microcontroller, now you have a robotics playground as well.