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Numi v3: Automated AI Coin Sorting Prototype

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In summer 2024, I shared my journey of building an AI-powered coin sorting robot, Numi v2. After several months of development, I paused the project because AI technology wasn't quite ready. However, by March 2-25, advancements in AI convinced me it was time to pick the project back up.

The past two months have been an intense sprint to complete Numi v3, just in time for the Colorado Springs Coin Club Show and the ANA Summer Seminar. I'm thrilled to announce that after hundreds of hours of work, Numi v3 is ready for its public debut!

I'll be demoing Numi at:

Colorado Springs Coin Club Show [June 27th–28th, 2025]
ANA Summer Seminar [June 28th–July 3rd, 2025]

If you can’t attend, check out this video demo!

Why I Created Numi

I'm a passionate coin collector and technologist [former Digital Product Manager]. I believe strongly in the potential of Artificial Intelligence to positively impact our hobby. Many people still underestimate the potential benefits of AI to the hobby.

Numi v3 will initially focus on Lincoln Wheat cents, sorting them efficiently by year and mint mark.

How Numi Works

Numi v3's sorting chassis is constructed from over 500 LEGO pieces, powered internally by a Raspberry Pi 5. I wrote the software in Python with help from Cursor AI, totaling approximately 14,000 lines of code.

When starting Numi, you'll first encounter a welcome page offering two operational modes: Standard Mode and Dealer Mode.

Mode Selection

Standard Mode

Standard Mode handles Numi’s essential functions:

Controlling LEGO motors to guide coins smoothly through the machine
Using dual cameras to capture high-resolution photos when coins enter the viewing area
Basic user interface for displaying and saving photos securely to Google Cloud
AI analysis of coin images via Google Gemini 2.5 Flash (a powerful and affordable image recognition AI from Google)
Automated sorting by decade and year
Fully automated looping process for continuous sorting

Creating Standard Mode was by far the biggest challenge. I had to meticulously engineer every mechanical detail and software component from scratch. Once established, it laid the groundwork for easily adding other useful modes.

Dealer Mode, designed in collaboration with feedback from coin dealers nationwide, enables dealers to quickly identify valuable coins within bulk lots.

In Dealer Mode, you start by specifying coins of interest through a custom watch list: Once running, Numi alerts you when it identifies coins matching your list, capturing detailed images and tracking analysis costs (approximately $6 per 10,000 coins analyzed). Numi can analyze roughly one coin every 15 seconds, or around 5,000 coins per day.'

Customizable Watchlist

Customized Report

After processing, you can generate a custom Google Sheet report listing discovered coins along with image links.

Dealer Mode is configured for real-time feedback at demonstrations, helping me refine Numi based on practical insights from actual dealers.

With the core system in place, developing additional modes is straightforward. One idea I'm particularly excited about is Collector Mode, which would help collectors complete coin albums interactively. Users would see a digital album highlighting missing coins, dynamically updated as Numi sorts and identifies them.

I’m eager to hear your ideas or additional scenarios you'd find helpful!

Consider Numi v3 a working prototype and proof of concept. My main goal at upcoming events is to gather community feedback on the broader impact of automated AI coin sorting and its future potential.

This project has undergone significant evolution over the past two years. Initially, Numi v1 was a customized ChatGPT-powered coin grader. Numi v2 automated silver coin sorting from circulation. Each iteration brought valuable lessons that shaped this latest version. The goal has already remained the same though: to make AI genuinely beneficial and approachable for everyone in our hobby.

Looking ahead, I'll focus on refining Numi based on real-world tests. Collectors from around the country have reached out with interest in helping them sort through their bulk wheat hoards. I’ve had dealers offer to have me come in and run through their bulk wheaties to get concrete numbers on how time is saved and extra revenue generated.

Thank you for following my journey with Numi v3. Please share any suggestions you have and I hope to meet you at the show or seminar!

Justin, aka Dansco Dude

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Let's get in touch!

justinphinh@gmail.com