The original Mechanism was made out of metal, but you had to work with plastic toys. How did that affect your design? Regular Lego bricks are problematic because they constantly want to pop apart, so I had to use cross-bracing to keep everything rigid enough to withstand all the mechanical force. And unlike my previous machines which were made from classic bricks, the new machine is purely made from Lego Technic pieces because the gearing is so complicated. I also designed it using a modular system with racks of gears that I could remove or pop back in easily. For example, I made one module that does nothing but divide by 19. It makes the design problem smaller: all I have to do is focus on getting each module right, then figure out the next one. The hardest part was physically linking the output of one module to the input of the next; sometimes the output of one bit was physically far away from the input of the next one. But modularity really was the secret to making it all work. (via Watch an Apple Engineer Recreate a 2,000-Year-Old Computer Using Legos | Co.Design)