A Solopreneur Built a "Second Brain" That Sorts Voice Memos by Email Subject Line

A Solopreneur Built a "Second Brain"

That Sorts Voice Memos by Email Subject Line

The creator behind The AI Maker — a Substack publication that grew from zero to more than 9,700 subscribers and $30,000-plus in annual recurring revenue in eight months — built something most solo creators only describe.

A working second brain.

In a Substack post titled Building AI Second Brain: How I Turn Voice Memos Into Substack Notes and Business Ideas, the writer behind The AI Maker documented the exact automation that pipes spoken thoughts from an iPhone into four different content destinations — without the creator deciding, in the moment, what kind of content each thought is.

The routing happens by email subject line.

The capture: Wisprflow and Apple Notes

The front end of the system is unglamorous on purpose. The creator records voice memos using Wisprflow, an AI dictation tool available on iPhone and Android that produces clean transcribed text in real time. The transcripts auto-save into Apple Notes.

That's the entire capture step. No app to open. No dashboard. No project picker. The friction between "I have a thought" and "the thought is captured" is roughly the time it takes to unlock the phone.

The choice of Apple Notes as the holding tank is the load-bearing decision. It's universal, it syncs across the creator's devices automatically and — critically — it can be emailed.

The routing: subject line as control panel

This is where the system gets clever.

When the creator has a voice memo they want to act on, they email it to a dedicated address inside their Make.com automation. The email's subject line tells the automation what to do with it.

If the subject contains substack, the memo is routed through one prompt chain that turns it into 10 strategic Substack Notes hooks. If the subject contains business, a different chain transforms it into 3-5 validated business concepts. Newsletter triggers a complete newsletter brief. Memo sends it to a "thoughts and ideas" database for later organization.

The same voice memo, in other words, could become any of four different artifacts depending on a single word the creator typed at the top of an email. Multiple keywords combine to produce multiple outputs from the same recording.

"Users can control which outputs they want through the email subject line," the creator wrote, describing the system in the published Substack post.

The engine: Make.com and four OpenAI modules

The middle of the pipeline is a Make.com scenario with four OpenAI modules and four Notion databases. Each module is tuned with a distinct prompt that produces a distinct artifact:

• One for Substack Notes
• One for the newsletter brief
• One for business idea validation
• One for general memo organization

The OpenAI modules don't talk to each other. The keyword router decides which ones to fire. The outputs land in their respective Notion databases, where the creator reviews them later.

The system is, in the technical sense, just a fan-out automation with a keyword switch in front of it. What makes it interesting is the user experience design wrapped around the engineering.

The user experience trick

Most automation tutorials trip on the same problem: the automation works, but the human has to remember a complicated workflow to use it. The keyword-in-subject-line approach solves this by collapsing the workflow into something everyone already knows how to do — type a word at the top of an email.

There's no app to open. No form to fill out. No interface beyond the one that already shipped with the phone.

The creator's voice gets to the AI through Wisprflow and Apple Notes. The creator's intent gets to the AI through the email subject line. The two channels are completely separate, which is precisely why the system stays out of the way.

Eight months from zero

The publication that documents the system — The AI Maker — has a track record that lends the workflow some credibility. In a separate post titled 8 Lessons in 8 Months Growing My AI Substack from ZERO to $30K+ ARR and 9700+ Subscribers, the same creator catalogued the growth.

The second-brain automation is, by their account, part of the engine behind that growth. Voice memos captured in dead time become Substack Notes that travel. Business ideas that would have evaporated get logged. Newsletter briefs that would have required a dedicated writing session get drafted in the background.

The creator still edits everything before it goes out. The automation doesn't publish. It produces drafts and routes them to the right database, where a human can decide what's worth shaping into a finished piece.

Why this matters for creators contemplating automation

The post on The AI Maker lands at a moment when most creator-automation tutorials are either too simple to do real work or too complex to actually deploy. This one occupies a useful middle: real engineering, real outputs, but a front end so light it disappears.

The deeper insight is the separation of concerns. Voice handles input. Email subject lines handle intent. Make.com handles routing. Notion handles storage. Each layer does one thing well, and none of them require the creator to remember how the system works while they're using it.

For a solopreneur, that's the difference between an automation that runs and an automation that sits, broken, in a tab that never gets opened.

The takeaway

The AI Maker's second brain isn't an AI breakthrough. It's a UX breakthrough wrapped around AI plumbing that's now widely available. The voice goes in. The keyword does the steering. The drafts come out. The creator picks what to publish.

In a content economy where most creators are still typing every word, the workflow points at something quieter: the bottleneck was never the AI. It was the friction in front of the AI. Remove the friction, and the creator's voice — captured one walk, one drive, one waiting room at a time — turns into a content engine that runs on dead time.

Source: The AI Maker, Building AI Second Brain: How I Turn Voice Memos Into Substack Notes and Business Ideas, Substack. https://aimaker.substack.com/p/ai-automation-voice-memo-to-second-brain-notion-substack-notes-newsletter-business-ideas-wisprflow

Related: The AI Maker, 8 Lessons in 8 Months Growing My AI Substack from ZERO to $30K+ ARR and 9700+ Subscribers, Substack. https://aimaker.substack.com/p/substack-ultimate-growth-guide-2026