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
Structural SteelBook
The best Structural Steel reference on app store! Now for iPhone, iPad & Mac! Buy once, run on all your devices, no in-app purchases / limited features gimmicks!
$4.99 · In-app purchases
PRICE
$4.99
In-app purchases
BUSINESS MODEL
Paid
No overall Grossing estimate available
RATING
★ 4.7
6 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 included17 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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Quick prompt
Good fit for mobile-first iOS and Android prototypes with managed app scaffolding.
// RORK SYSTEM PROMPT
Rork plan preview for Structural SteelBook: map the core Reference 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
Implement advanced search and filtering options.
Assumption to check: Limited search functionality may frustrate users
Validate with people who use this workflow before building.
Hypothesis 2
Enable offline mode for accessing saved data.
Assumption to check: Lack of offline access limits usability
Validate with people who use this workflow before building.
Hypothesis 3
Provide clear explanations of premium features and trial options.
Assumption to check: In-app purchases can be unclear to users
Validate with people who use this workflow before building.
Hypothesis 4
Revamp UI with modern design trends and improved user experience.
Assumption to check: Design may feel outdated
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
The best Structural Steel reference on app store! Now for iPhone, iPad & Mac! Buy once, run on all your devices, no in-app purchases / limited features gimmicks! From the developer of [steel shapes], the highest rated Structural Steel app since 2009. Now with the latest AISC v15 library, more than 20000 steel entries in 19 libraries & MANY new features. SteelBook contains the latest (v15), previous (ASD 5 - 9, LRFD 1 - 3, v13, v14, v14.1) and HISTORIC American Institute of Steel Construction's Structural Steel Databases in a fast, easy to use interface. LIBRARIES: ---------------------------------------- AISC LIBRARIES: - Current version 15 & 15-SI (NEW!) - Versions 13.2 & 13.2 SI, 13.1.1, 13.1.1 SI, 13, v14 & v14-SI, v14.1 & v14.1-SI - LRFD 1st through 3rd Ed. - ASD 5th through 9th Ed. - HISTORIC UNIT SYSTEM SWITCHING: ---------------------------------------- Properties can be displayed in either the original English units or converted to metric with the tap of a button (libraries 13.2 & newer) SORTING: ---------------------------------------- Sort sections within a library given a specific property in ascending / descending order. QUICK SEARCH: ---------------------------------------- SteelBook also lets you find a section with a quick search function, where, for example, "W16 x 89", "W16x89" or simply "W1689" will locate the same section or its closest approximation. NEW! SIDE BY SIDE EQUIVALENCIES ---------------------------------------- Display Equivalent Imperial / Metric designations side by side while browsing NEW! FRACTIONAL DETAILING VALUES, PROPERTIES & UNITS ---------------------------------------- For library version 15, support for v14 coming soon NEW! PRINT & SHARE ---------------------------------------- Print a section's properties & cross section or Share as a PDF NEW! DARK / LIGHT MODE & DYNAMIC TYPE SUPPORT ---------------------------------------- SteelBook's UI adapts to your device's setting, whether you prefer Dark, Light or adaptive color scheme, SteelBook will naturally adapt to it. Also new is Dynamic type support, SteelBook will adapt its interface to your device's accessibility settings. NEW! UNIVERSAL APP, BUY ONCE, RUN EVERYWHERE ———————————————————— The Steel app for the next decade, run on iOS/iPad (iOS/iPad OS 16 and newer) and on MacOS (10.13 / Ventura). ***************************************** visit us at: www.TheMobileEngineer.com
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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.
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BUILD KIT DIFFICULTY
Starter
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.
