The Sparrows Hall Pass is a handy credit card sized tool used for opening doors by manipulating the latch. In my wallet, I carried the Hall Pass as well as a Schlage and Kwikset key depth gauges. The key gauges seemed unnecessarily large, and it looked like I could combine these three tools without severely reducing the structure of the ‘Hall Pass’
I started by drawing the original design in SolidWorks, then added the stepped key gauge. Minor design changes were made after a few cardboard prototypes were made and tested, but after that it was off to be lasercut. I had ten of these cut out of .035″ Stainless Steel for $62 from a seller on Ebay.
When I received the parts, they were blank. To label the key types and depths, I laser engraved them. Our laser is only 45 watts, and is not powerful enough to etch steel on its own, so we use a product called CerMark. CerMark paints onto the steel and is allowed to dry. The design is then engraved to the part, and the excess CerMark is rinsed off. The result is a dark and durable etch on the steel.
Overall, I am very pleased with the results I received. Having a single tool to carry around is significantly easier than having 3 bulky pieces of steel. If I were to make another version, I would add a hexagonal hole large enough to accept a standard screwdriver bit somewhere on the part so it can be used as a pocket screwdriver.