I created a simple LED circuit with a tilt ball sensor that's attached to the back of a button cell battery holder. Setting it upright lights the LED, turning it upside down turns the LED off. My wife wanted to have it as part of an emergency nightlight next to the bed, in the shape of a turtle. I used that as an excuse to develop my skills with Fusion 360, now that 123D Design is no longer supported.

Both body and shell need to have supports enabled when printing. There are two versions of the shell, one with bumps to allow it to sit on it's side as well as back, and another that's mostly smooth, just one flat spot on the top to help it adhere to the bed when printing. I printed the body in green PLA and the shells in glow-in-the-dark PLA. The tolerance at the head for fitting the shell is tight to ensure a seal that doesn't need to be glued.

Electronic parts:

• Button cell battery holder: [https://www.digikey.com/classic/Ordering/AddPart.aspx](https://www.digikey.com/classic/Ordering/AddPart.aspx)
• Battery: CR2032 coin-cell battery
• Tilt ball switch: Search ebay for "tilt ball switch sw-530d"
• LED: Any color LED, as long as it can light up with 3 volts supplied by the battery
• Optional pin header: Female pin header can be used to allow you to exchange LED colors