This Transparent Combination Lock Model Clearly Explains What Goes Inside

Theodore Gray develops interactive miniature models of mechanical devices. His transparent combination lock model shows how the locking mechanism works using clear acrylic plates.
Kashyap Vyas

School lockers were always a mystery. You just rotate the knob in some specific order and there! Your locker room is opened right in front of your eyes.

We always had the thought of how this magical feat was achieved when we used one. But in reality, the mechanism is pretty simple and straightforward.

Some of you might have even looked up videos on how the locking mechanism engages and disengages. However, many do struggle to decode the idea even from videos, as the mechanism needs to be understood from the working of three or four wheels.


To help the doubtful minds, Theodore Gray from has developed a transparent replica model of a combination lock that clearly explains how the system actually works.

The model is made from clear acrylic pieces carved out using a precision laser. The wheels follow a combination so that the lock only opens when the correct sequence is used.  

Even if you turn the dial back and forth, the device will only unlock when the correct combination is used. The acrylic model also makes use of different colored acrylic plates, making the whole system look pleasing to the eye whilst making it very simple to understand and spot different parts of the system.

Theodore Gray also sells such replica models through his website. There are two versions of the product available – the 45$ kit that needs assembly and the 80$ kit that comes assembled right out of the box.

Apart from the combination lock replica, he has made countless projects that explain various complex systems around us in a very easy to understand way. Since the working models that he designs are scaled down to sizes that you can hold in hand and tinker with, it’s the best solution to learn complex systems in an interactive way.

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The Two-Speed Transaxle setup is another interactive replica that demonstrates the working of a Transmission and Differential used in automobiles.

This Transparent Combination Lock Model Clearly Explains What Goes Inside
Source: Mechanical Gifs

Differentials and transmission systems are very complex in their design, and they are often hard to explain without a proper working model. With Theodore’s working models, the process can be simplified multifold.

There’s also a radial engine model that takes the cake for being one of the most complex, yet elegant replica models. It essentially explains how radial engines function without crankshaft, using just a ‘spider’ that links all the connecting rods together.

This Transparent Combination Lock Model Clearly Explains What Goes Inside
Source: Mechanical Gifs

The best way to enjoy his models is to buy one kit that you must put together yourself. The whole process of assembling makes you feel like you are part of the project. The step-by-step instructions given on the website will help you build it in no time at all.