LEGO Logic Gates - Half Adder

A half adder I built from LEGOs. The half adder is built form only OR and NOT gates. The amount of mechanical imprecision and friction in the half adder suggests that a full adder with a similar design would have issues functioning.
If you are interested in building one, here's where I ordered the parts from: www.bricklink.c...
Inspiration:
www.nand2tetris...
randomwraith.co...
keshavsaharia.c...