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
FunkBox Drum Machine
Funkbox contains all your favorite vintage drum machine sounds in one funky quirky little app! FunkBox is a full featured drum machine that you can use to compose, record and play your songs live
$4.99 · In-app purchases
PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.2
68 ratings · Top 30%
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 included18 files
A product spec, phased build plan, differentiation notes, and screen references.
- START_HERE
- AGENTS
- EVIDENCE
- SPEC
- BUILD_PLAN
- DIFFERENTIATION
- skills/
- screens/
Preview a sample Build Kit No email needed
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 FunkBox Drum Machine: 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
Offer a wider variety of sounds and user-uploaded samples.
Assumption to check: Limited sound selection and customization options.
Validate with people who use this workflow before building.
Hypothesis 2
Include a way to share and collaborate on drum patterns.
Assumption to check: No collaboration features for sharing patterns.
Validate with people who use this workflow before building.
Hypothesis 3
Simplify the UI/UX for better navigation and usability.
Assumption to check: User interface can feel cluttered.
Validate with people who use this workflow before building.
Hypothesis 4
Provide clear explanations of what each purchase unlocks.
Assumption to check: In-app purchases can be confusing.
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
Funkbox contains all your favorite vintage drum machine sounds in one funky quirky little app! FunkBox is a full featured drum machine that you can use to compose, record and play your songs live. It has been used in the studio by electronic artists such as Gorillaz (on their album “The Fall”) Tom Middleton (Global Communications, Jedi Knights) and Steve Cobby (Fila Brazillia), and also by alternative/indie musicians such as tUnE-yArDs, Mark Lanegan (Screaming Trees, QOTSA), Anton Newcombe (Brian Jonestown Massacre), and Reggie Pace (Bon Iver, No BS Brass). It's also been used on stage by rock/pop musicians such as Joan Osborne and Glenn Tilbrook (Squeeze) live in concert. Its quirky vintage sounds, ease of use and advanced features have made it popular with many musicians worldwide who use it to make all sorts of different styles of music. FunkBox was featured in Computer Music Magazine's "Amazing Music Apps" special issue and Electronic Musician magazine's "Attack of the Killer Apps" best music tools for the iPad. FunkBox 4.0 features: The look, feel, sound and quirks of a classic vintage drum machine. iOS 10 compatible, iPhone 5 retina graphics compatible, iPad retina graphics compatible. Universal app that works great on iPad, iPhone, and iPod Touch. Buy it once and you can use it on all your iOS devices. Fourteen classic boxes to choose from, including favorites like the 808, 909, CR-78, LM-2, MRK-2, DX, TOM, and more. Create your own custom boxes by mix and matching preset samples, or even import and use your own custom samples. Includes 36 preset rhythm patterns, plus several more bonus banks. Easily edit the included patterns to create your own beats. Export your drum loops as audio or midi via email, audio pasteboard, or the iTunes folder. Easily share your custom boxes and patterns via email with your friends, or between your devices. Use Audiobus 3 and Inter-App Audio to exchange live audio with other apps. Use Ableton Link or CoreMIDI to sync up with “real” music equipment or other music apps, multi-tasking in the background or on other nearby iOS devices. Use the bonus MIDI bass sequencer to play a bassline along with your beat using another iOS app or a “real” hardware synth! …and lots more. Need some old school beats? Grab yourself some funk in a box.
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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
react-navigation
expo-av
@react-native-async-storage/async-storage
shadcn/ui
BUILD KIT DIFFICULTY
Advanced
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.
