Milk Bottle Lock

Ever worry about food thieves in your office stealing the milk you keep in the office fridge? This is the perfect solution for you!

• 3D printing (SLA/FDM)
• M3 nuts and screws
• M3 threaded insert
• 1.7mm aluminium rod
• 6.4mm steel ball

I found this material in my garage, you can always use whatever you have around you.

I came across some bottle lock designs online, and many of them resemble what Odom did in his Instructables tutorial (https://www.instructables.com/Beer-Bottle-Lock/).

While it's a great concept to keep your bottle secure, I find the design a bit too aggressive for my taste. I don't want to become known as the stingy person in the office! So, I had an idea to create a puzzle lock that only I (or some clever individuals) can open to access the milk.

After examining the bottle and its cap closely, I noticed a small gap between them that could be used for gripping. I thought about incorporating a hook with a pivot in the middle. By applying force to one end of the hook, it could grip the gap securely. To achieve this, I planned to use a steel ball on an inclined surface to push the hook into position naturally when the bottle is oriented correctly. To release the lock, I'd simply flip the whole mechanism upside down, causing the steel ball to move in the opposite direction. To ensure a firm grip, I considered implementing four of these mechanisms at 90-degree offsets around the cap, preventing it from sliding out.

With this design, I can have a unique and fun way to secure my milk bottle while adding a bit of challenge to those who try to open it!

The lock consists of 4 parts:

1. Base: Where the steel balls are placed
2. Top: Covering the base, providing a cavity for the steel ball to move
3. Grip: The 'hook' describes in the previous part
4. Cover: To cover the entire lock

I 3D printed the top, base and grip with clear resin and the cover with PLA.

While this bottle lock may not be compatible with all types of bottle caps, it perfectly fulfils my requirements. I hope it serves as inspiration for you to develop your own design. Till next time!