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
Thereminator 2
“I’ll be Bach.” Stop the presses! Load up the inkwells! For it's the return of one of the first — if not the first — instruments made for iOS: the infamous “pocket theremin” is back.
$7.99 · In-app purchases
PRICE
$7.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.7
12 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 included19 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 Thereminator 2: 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 customizable effects.
Assumption to check: Limited sound effects compared to competitors
Validate with people who use this workflow before building.
Hypothesis 2
Implement onboarding tutorials to help new users.
Assumption to check: No tutorial or guidance for beginners
Validate with people who use this workflow before building.
Hypothesis 3
Optimize audio processing for smoother playback.
Assumption to check: Occasional audio latency issues
Validate with people who use this workflow before building.
Hypothesis 4
Simplify the paywall and clarify subscription benefits.
Assumption to check: In-app purchase model 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
“I’ll be Bach.” Stop the presses! Load up the inkwells! For it's the return of one of the first — if not the first — instruments made for iOS: the infamous “pocket theremin” is back. A lot has changed since those heady days of 2008, and so has Thereminator. Although it is not made of T-1000 grade liquid metal (well...not yet), the all-new Thereminator 2 has evolved into a bona fide touch controlled virtual theremin with ample helpings of tone, expression, versatility, and technology. And it’s now an AUv3 plugin, too! Using a special adaptation of the MPE protocol, Thereminator 2 can inject its eerie sounds directly into your DAW, whether on your iPhone, iPad or Apple Silicon powered computer. Whether you have your plan 9 ready, or just lurking in dark shadows, it is a thrill to bring back the app that started it all for us. Thank Y’all for the support, for it’s been an amazing journey! :: Specifications :: • Touch-controlled Virtual Theremin • AUv3 instrument plugin included • Compatible with DAWs that are MPE friendly, including GarageBand, Logic, and Cubasis • Compatible with iPhone, iPad, and Apple Silicon powered computers • Over 50 factory presets Sound engine includes, • 8 waveforms, including the original, unique Thereminator waveform • 8 octave frequency range • Special drive stage for fattening up the sound • Virtual-Analog resonant filter • Dedicated vibrato and tremolo operators with adjustable rate & amount • Portamento • Custom chorus / expander effect for big stereophonic sounds • Modeled tape delay capable of self-oscillation — plenty of vintage mojo • Vertical touch control for volume, filter, vibrato and tremolo Built-in touch controller includes, • Horizontal pitch and vertical expression control • 51 musical scales • Selectable musical key • Note Snap feature that can dial in any amount of glide between adjacent notes • Lock feature to preserve above setting during preset changes • Scrollable control surface with adjustable key size MIDI / MPE and other features include, • MIDI Learn • MPE • Can be used with regular MIDI keyboards on MIDI channel 1 (channels 2-16 are optimized for MPE) • Save & share unlimited banks and presets • Standalone app includes virtual “Tapedeck” for recording & sharing your creations
Written user reviews are not shown here. Check current App Store reviews >
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
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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.
