Objective

Design a machine that enables the creation of a token economy within Kidzu Children’s Museum’s space-themed mobile museum. This “Token Taker” must collect tokens at each station, provide instant gratification to indicate activation of the station, have tactile elements, and match the museum's outer-space aesthetic.

Design Criteria

To begin the brainstorming process, our team identified a list of design constraints and criteria, each with a corresponding performance criteria.

1. Kid safe → No loose parts smaller than 1 cubic inch

2. Indicate the station is activated → Electronic output lasting 2-5 seconds

3. Durability → Lasts 6 months without maintenance

4. Token storage → Holds 40-50 tokens

5. Match aesthetic of truck → >70% of surveyed individuals agree

6. Accessible for 5th graders → Mounted at 4-4.5 feet high

7. Temperature resistant → Withstands 100°F

8. Reproducibility → <$250 per unit

To ensure our Token Taker effectively met Kidzu’s needs, we conducted a multi-stage ideation process that began with research and extensive conservations with our client. We then broke the Token Taker down into 6 separate design blocks, “brain-dumped” ideas onto notecards for each design block, and then created screening and scoring matrices to identify the optimal solution.

Ultimately, we decided to create a Token Taker machine with the following features:

• A flat slide/funnel with an opening just big enough for the tokens to slide in

• An optical/beam-break sensor to detect the token and activate LED lights behind a button

• When the user presses the button, it triggers LED lights around the machine and a speaker

• A drawer with a hidden latch/key opening mechanism to store and remove the tokens

Prototype #1: Low Fidelity

Purpose: Establish proof of concept, determine sizing of components

First CAD model

I designed the storage system for the Token Taker, which Kidzu staff identified as needing to hold at least 40 tokens, slide smoothly, be easily accessible for staff, and restrict children from opening it. To do so, I developed a rail-guided drawer system in OnShape. Originally, I did not include the rails, but early testing showed that a barrier was needed to prevent the drawer from moving in the up/down and left/right dimensions. To prevent children from tampering with the Token Taker and attempting to take tokens from the drawer, I designed it with an inset handle and barrel lock, so that it blended into the side of the Token Taker and could only be opened with the staff’s key.

Conclusion

Later iteration with rails and integration with barrel lock and Token Taker housing

Side view of final storage system

Front view of final storage system

This project marked my first experience with the full product development process, and it was instrumental in shaping how I approach engineering problems. Building the Token Taker taught me how to start with a problem, identify the optimal solution, then effectively create, iterate on, test, and present that solution, all while collaborating with a cross-functional team. The project strengthened both my technical and project management skills, and reinforced how much I enjoy combining technical and creative skills to solve a unique problem, which is the mindset that’s become central to how I approach all of my engineering work.