Feature spec
Goal: Send a clear invoice after finishing a job.
- Add a client, line items, a due date, and payment instructions.
- Preview the total before exporting a PDF.
- Keep an editable draft if export fails.
App Overview
Chladni Screen
Chladni figures were geometric figures first discovered by Robert Hooke in 1680 and was researched and published by Ernst Chladni in 1787.
$1.99 · In-app purchases
PRICE
$1.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.6
81 ratings · Top 15%
Evidence scope: No current overall US chart position is available. Category-chart positions shown in discovery are a separate scope. Revenue is a directional model estimate, not verified earnings.
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Build Kit
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A product spec, screen plans, and build steps for your coding agent.
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What's included15 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
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Illustrative example: an invoice app for independent contractors. Your kit is tailored to the app you choose; this is not its generated content.
Screen plan
Invoice editor: Client at the top, editable line items in the middle, total and preview action at the bottom.
States: Empty draft, validation errors beside each field, exporting, and a retry action that preserves the draft.
Differentiate and validate
Hypothesis: Contractors need faster repeat invoices more than more templates.
First experiment: Test duplicating a previous job with five contractors. Watch where they hesitate before expanding the feature set.
The full kit adds a phased build plan, evidence notes, tool prompts, and implementation guidance. It is a plan for your coding agent, not a finished app.
Usage: Mechanics are fair game; never reuse the original name, branding, assets, or verbatim copy.
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Free quick prompt For a smaller starting point
Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Chladni Screen: map the core Music workflow, choose the smallest differentiated feature set, define the data and monetization boundaries, then prototype the riskiest user journey first.
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Opportunities
AI-GENERATED OPPORTUNITY HYPOTHESES
These are generated suggestions, not verified review quotations. Check current App Store reviews and speak with users before treating a possible gap as a requirement.
Hypothesis 1
Provide more sound packs or frequency settings.
Assumption to check: Limited sound customization options.
Validate with people who use this workflow before building.
Hypothesis 2
Simplify pattern saving and provide better organization.
Assumption to check: Complexity in saving and managing patterns.
Validate with people who use this workflow before building.
Hypothesis 3
Enable users to share their patterns on social media.
Assumption to check: No social sharing features.
Validate with people who use this workflow before building.
Hypothesis 4
Expand the frequency range for more diverse visualizations.
Assumption to check: Limited frequency range.
Validate with people who use this workflow before building.
App evidence
Original App Store material. Ratings and screenshots describe the existing app, not proof of demand for your version.
App Store description
Chladni figures were geometric figures first discovered by Robert Hooke in 1680 and was researched and published by Ernst Chladni in 1787. These geometric figures are typically rendered on a rigid, vibrating membrane made from materials such as metal, plastic, glass, or bowl, covered with grains, like salt and sand, and changes shapes in response to different sounds that are transmitted by mediums such as speakers and actuators. The study of such phenomena is also known as cymatics. Chladni is able to simulate the phenomena digitally. A further 3 programs can be displayed by pressing and holding each of the 3 mode buttons. Some texts in this document are taken from the following Wikipedia Creative Commons license (inheritance). https://en.wikipedia.org/wiki/Ernst_Chladni Explore the wonders and beauty of the Chladni figures as it manifests from varying sound sources such as your voice and instruments!
Written user reviews are not shown here. Check current App Store reviews >
Screenshots
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Build scope
Plan a focused first version with your coding agent. These are planning assumptions, not a delivery guarantee.
Define the first version
Choose one audience and one core workflow. Use the kit to agree on its screens, data, and acceptance criteria before building.
Set boundaries
Decide which secondary features, integrations, and platform support can wait. Your version does not need to reproduce everything in the original.
Check the hard parts
Validate external services, specialist technology, data access, and ongoing costs for your chosen scope.
SUGGESTED BUILD STACK
React Native
Expo
Zustand
expo-av
react-navigation
expo-sensors
BUILD KIT DIFFICULTY
Intermediate
From the Build Kit assessment.
A reliable timeline needs an agreed scope and a technical check. Ask your agent to estimate the phases in BUILD_PLAN.md after that review.
