Real AI agent use cases, with sources and setup prompts

Build a body-fat estimate app from photos

A 17-year-old vibe-coded with Claude a fitness app that estimates body fat percentage from three photos.

See pricing pageweeksIntermediateSource linked

Source

@ravexionex on X · 2026-06-16

Written in our own words. Credit to the original author. Link checked 2026-10-14.

What they did

A 17-year-old vibe-coded with Claude a fitness app that estimates body fat percentage from three photos.

Result (as claimed)

Reported by a third party; accuracy not independently shown.

Tools they used

Claude

Cost: Pricing depends on the tools you pick; check each official pricing page.

Set it up

  1. Write a one-page brief

    Describe the app in plain words: who it is for, the 3 core screens or actions, and what "done" looks like.

  2. Start the project with your agent

    Open Claude and paste the brief. Ask it to propose a stack and a file plan before writing code.

  3. Build one slice at a time

    Ship the smallest working flow first, run it, then add features one by one. Commit after each working step.

  4. Test it like a user

    Click through on desktop and phone. Ask the agent to add basic tests and fix anything that breaks.

  5. Check security and ship

    Keep keys in environment variables, check auth and database rules, then deploy and share the link.

Copy the full setup prompt

Paste into your agent and it will walk you through the setup, asking before anything that sends, posts or spends.

You are helping me set up this AI use case end to end in Claude Code.

Goal: Build a body-fat estimate app from photos
What the original author did: A 17-year-old vibe-coded with Claude a fitness app that estimates body fat percentage from three photos.
Reported result (as claimed by the author): Reported by a third party; accuracy not independently shown.
Source: https://x.com/ravexionex/status/2066905642959290779
Tools they used: Claude
Category: Vibe coding & apps

Please:
1. Ask me 3 short questions about my situation (accounts I have, budget, what I want the output to look like).
2. Propose a step-by-step plan using these tools or cheaper alternatives, with the time and cost of each step. Use official pricing pages; say "check pricing" if unsure.
3. Then do the setup with me one step at a time, waiting for my OK before anything that sends messages, posts publicly, spends money or deletes data.
4. Finish with a checklist to run it again next time.

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