Amazon.com: Build MISINI 27-Piece Set CADA Power Functions Pro, High-Speed L/M/Servo Motor Set (Including Cross Shaft), 2.4G Fast Charge Remote Control Battery, Compatible with Lego Technology Cars : Toys & Games
Plastic Micro Servo Adapter for LEGO Cross - 16mm long : ID 4252 : $0.75 : Adafruit Industries, Unique & fun DIY electronics and kits