Series LTS | Tilt Switch Probe senses either the presence or absence of material. Airtight, dust tight, and waterproof. Applications include large hoppers, silos, crushers, trippers, stackers, and conveyors. | Dwyer Instruments
TILT SWITCH USING ARDUINO UNO R3 : 5 Steps - Instructables
Tilt ball switch : ID 173 : $2.00 : Adafruit Industries, Unique & fun DIY electronics and kits