Everyone has read the same list of mental models. Inversion, second-order thinking, the map is not the territory. Useful, general, and available on a thousand blogs for free.
What nobody has written down is how those models play out in your specific industry. The idea is to build a Google Sheet of mental models for one niche, written by someone who's actually worked in it, and sell it to the people coming up behind you.
It's one of the 100 business ideas in Google Sheets on my list, and it's the one that best rewards experience over hustle.
The idea
General mental models are good. Niche mental models are great.
Contextualize, analyze, and enrich mental models for a very specific audience. That's the whole product. Take a model everyone knows, and show how it actually applies when you're a junior recruiter, a first-year restaurant owner, or a product manager at a company with 40 people.
Take inversion. In the general version, you ask what would make a project fail and avoid that. In the version for a wedding photographer, inversion is a list of the eleven ways a wedding shoot goes wrong, ranked by how often you've seen each one, with the one thing you now do to prevent each. That second version is worth paying for. The first one is a tweet.
If you have five years in an industry, put that to use teaching the next era of people in your industry. You already have the models. You use them every day without naming them. The work is to name them, write down the story that taught you each one, and explain when the model breaks.
The audience is narrow on purpose. "Mental models for marketers" competes with everyone. "Mental models for the first 90 days as a marketing manager at a B2B software company" competes with nobody, and the person who fits that description will feel like you wrote it for them. Because you did.
Aim for 30 to 50 models. Fewer than that feels thin. More than that and the buyer won't get through it. Each one should have a name, a one-line definition, the niche version, a story, and a note on when not to use it.
How to build it in Google Sheets
Tabs
- Models: one row per model. Name, Category, General Definition, Niche Version, Example From Experience, When It Breaks, Related Models, Difficulty.
- Situations: the reverse index. One row per common situation in the niche ("client wants a discount", "shoot runs late") with a column pointing at the models that apply.
- Daily Model: a single tab that shows one model picked from the list, so the buyer can open it each morning and get one thing to think about.
- Notes: an empty tab where the buyer records their own examples. This is what makes it theirs.
Features to use
- Data validation dropdowns for Category and Difficulty, so the buyer can filter by "Beginner" on day one.
- VLOOKUP on the Situations tab, so typing a model's name pulls its niche definition alongside the situation without duplicating text.
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A random pick on the Daily Model tab using INDEX with RANDBETWEEN:
=INDEX(Models!A2:A, RANDBETWEEN(1, COUNTA(Models!A2:A))). It changes every time the sheet recalculates. - Conditional formatting on Difficulty so beginner models read green and advanced ones read red.
- FILTER on a By Category view, driven by a dropdown.
- Protected ranges on the Models tab so the buyer edits Notes, not your work.
Write the Example From Experience column last. It's the hardest and most valuable column, and you'll write better stories once the structure is in place.
Who pays for it, and how to sell it
The buyer is someone in their first two years in your industry, or someone switching into it. They're paying for the shortcut past mistakes you already made. Managers who onboard new hires are a second buyer, and they'll pay more, because they're buying for a team.
Price it as a one-time sheet somewhere between $29 and $99. Experience-based content holds a higher price than curated content, so don't price it like a list of links. If you add a few models a quarter and keep the Situations index growing, a small annual subscription works too.
Sell on Gumroad if it's a one-time purchase. If you want buyers to get a live, updating sheet without you manually sharing each one, sell it through OnlySheets, which handles payment and sharing in one step.
The service on top is obvious: a call with you. Sell the sheet, then offer a 30-minute session where you walk through the three models that matter most for the buyer's current problem.
For the first ten customers, write one model a week as a public post, niche version included, and end each with the story. Stories about specific mistakes in a specific industry get forwarded inside that industry. Put the sheet link at the end. The tenth post will do the work the first one didn't.
Related ideas from the list
- Business Book Summaries, the same idea of contextualizing general knowledge for one narrow audience.
- Prioritization Frameworks, a sibling collection of thinking tools sold to people who want to decide better.
- Oblique Strategies, one-a-day prompts in a sheet, using the same random-pick mechanic.
Want the other 99? This is one idea from my list of 100 business ideas you can build in Google Sheets. Get all 100 business ideas as a free Google Sheet.
And if you want to learn how to package and sell spreadsheets, my course Selling Spreadsheets walks through exactly that.