For Steph's birthday, she had requested an "experience" as her gift. I took this to heart, and created a box with 5 different pieces in 5 locations around Atlanta, and at each location, a clue to the next.
The completed box in its open and closed states
Each piece in the box has 2 snap fingers on each side to hold it in when inserted. Every time a piece is inserted, it pushes a spring-loaded block out of the way. Once all of them have been inserted, and the blocks pressed, the key can be placed. Rotating the key clockwise pulls the spring-loaded latch, using a single-tooth rack and pinion mechanism. When the latch (slider lock) is released, the lid pops open.
CAD of the fully assembled box in its open state
Cross section view at the top of the slider lock
Before the purple piece is pressed in, the key cannot get through
Once all pieces are inserted, the key can now engage the slide lock
Cross section of all engaged pieces
Cross section before fully inserted piece
Once pressed, the flex fingers must resist the force of the locking block springs
Example piece showing side flex fingers, and semi-circle opening for the key to pass through
The under side of the box, showing the key head and standoffs so the key can remain inside
Full assembly exploded view
Key Takeaways:
• Timeline and building a product for a deadline - this project was started 4 weeks prior to her birthday
• Trial and error - a few boxes were prototyped to finalize fit and finish of the design
• Seeing a completed product used and come full circle - allowing me to see where improvements could be made for a future iteration if need be
• Fun - as time consuming as this may be for a gift, it was really fun to make and use, and shouldn't be overlooked as one of the most important features!