Week 12-13 : Mechanical & Machine design

Many locations require XIAO products (such as RP2040 and ESP32-C3 modules), which motivates the development of a vending machine that is lightweight, low-cost, and easy to deploy worldwide. In addition, the system should be simple to operate, with efficient and user-friendly inventory management. Please refer to Chaihuo 2026 Mechanical Design, Machine Design week for more details.

The first prototype is intentionally simple and focuses more on the lightweight and deployability of the envisioned product : users tap an RFID card to confirm their purchase, after which a servo motor is activated to smoothly dispense XIAO RP2040s or ESP32-C3s.

Tim's involvement in the team is with the structural design and assembly, and this documentation focuses on the two iterations made.

First iteration : Aluminum extrusions

For the first iteration, the focus is on building a rough structural prototype using available materials and so aluminum extrusions was explored. Most of the extrusions on hand are either quite long (around 1 meter) or previously cut pieces with uneven ends, some even showing signs of melting from the cutting process.

Image of the extrusion

The shorter pieces were then used Despite these imperfections, they are still suitable for this stage since the goal is not precision, but to develop an initial visualization of the vending machine’s structure. Shorter pieces are also acceptable, as the final design will not require full 1-meter lengths.

One of the main challenges when working with aluminum extrusions is aligning the bolts and connectors, which can be time-consuming and imprecise, especially with uneven cuts. However, this iteration still serves an important purpose—it provides a tangible understanding of the overall form, particularly the top section of the vending machine. This initial build then informs the second iteration, where the design can be refined and improved with better fitting components and more precise assembly methods.

Second iteration : 3D-printed components

Lecture notes : REVIEW

A chassis is basically the structural skeleton or framework of a machine, device, or vehicle — the part that everything else attaches to. Think of it as the “bones” of your system. See video for timelapse

Here’s a breakdown:

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