Building Second Skin in public: an app for your tattoos 🌹

October 31, 2026 · 9 min read

Hi! 👋🏻 If you’ve read either of my last two posts, you’ve probably seen me mention Second Skin and then quickly move on to something else… well, this time it finally gets a post all to itself.

I’ve decided I’m going to build it in public. So every once in a while i’ll do a little write up to say how far i’ve gotten, which bits I got wrong along the way and what are some things i’ve learned. This first one is really just an introduction which also aims to show you what i’ve done so far 🚀.

Second Skin is an iOS app for keeping track of your tattoos. The tagline is “Your tattoos, from idea to healed.” and the app is split into four tabs that pretty much follow that journey:

Running through all of it is aftercare. When you finish a session you can start an aftercare routine (usually the one your artist gave you) and the app will remind you of each step every day until it’s healed. This is mainly just to help remind you as the app in no way will be giving medical information.

The Second Skin Welcome screen: a fan of three tattoo photos, the title “Second Skin”, the tagline “Your tattoos, from idea to healed.”, three features (Keep every piece, Plan what’s next, Look after it) and a Get started button The Welcome screen, with three of my own pieces. 🌹

🖋️ Why build it?

I’m a bit of a tattoo enthusiast myself, I started really just appreciating tattooing for what it is. I think that all started for me as I’ve always been into Hardcore & Metal music and tattooing is quite prominent in those scenes. This led to me being interested in traditional tattooing and then has led to me having quite a lot of tattoos myself. Every piece you see in-app as promotion will likely just be one of my own tattos.

Over the years getting tattoo’d i found that it was often hard to keep track of appointments, usually had to just add the booking into my own calendar and hope i’d remember. I then had to remember days before the session to do things like buy aftercare, buy food etc and prep for the session. I then had a bit of a hard time collating ideas I wanted to get in the longer term and also keeping track of pictures of the pieces I had. All of this led to me wishing there was something simple and beautiful in place to do all of this.

🏷️ Why “Second Skin”?

“Second skin” is actually the name for the protective film that goes over a fresh tattoo. I liked that the name also is resonant with tattoos being your second skin and since the app is about collection of your tattoos it makes sense that the app really is your second skin.

đź”’ Private by design

Tattoos can be pretty personal, so this was one of the first things I decided on: no sign-up, no ads, no tracking and no servers.

Everything lives on your devices and syncs through your own iCloud account using CloudKit’s private database. There are no Second Skin servers for your data to end up on, which also means I never see any of it. If you’re signed out of iCloud it all just stays on your device. The aim is for the App Store privacy label to say “Data Not Collected”, and for that to actually be true. I also think this is incredibly important as for a lot of us, our tattoos really are a thing we’ve done for ourselves, so I think storing this type of information should be the same.

The three privacy promises from the About you screen: Private to you (your details and collection live on your devices and in your own iCloud), We never see it (there are no Second Skin servers, nothing is sent to us) and No account, no tracking (no sign-up, no ads, no analytics on your photos) The privacy promises you see when you first set up the app.

🎨 The design

Before writing any code I sat down and tried to be inspired by some of my favourite apps. I used the help of AI to just collate a mood board of all different designs the apps I really love have used. This then let me mock up a few different ideas for how Second Skin will look. In the end the clean native look won for me. I think if the app is going to hold lot’s of your tattoos, lot’s of information and potentially lot’s of colourful things, I would prefer that the app itself is quite clean and stripped back so you can see exactly what you are looking for. Thefore….

  1. Photos lead. Your tattoos are the hero, so the app is built around big rounded photo cards and grids.
  2. Liquid Glass for controls only. The tab bar, toolbar buttons and floating controls get glass, and anything sitting on top of a photo gets a plain frosted material instead, as the HIG suggests.
  3. Colour in small doses. The surfaces are neutral, with one rose accent (#D9485F) for primary actions and whatever’s coming up next.
  4. Standard iOS type sizes only. No custom font sizes, so Dynamic Type just works.

🧱 The tech

For anyone curious, here’s what it’s being built with:

SQLiteData was probably the biggest decision so far. SwiftData would have been the obvious pick, but SQLiteData gives me live queries that work inside my @Observable screen models (not just in views), plain SQL for all the stats sums and counts, and CloudKit sharing. That last one means one day you could share an idea with your artist without me needing to run a backend. The trade-off is writing my migrations by hand in SQL, which to be fair has been a nice refresher.

💡 Tip: CloudKit only lets you add to your schema once it’s in production, you can’t rename or delete fields. If you’re syncing with CloudKit, it’s worth spending a bit more time on your data model up front before anything ships.

🤝 How I’m building it

In my last post I mentioned the one rule I set for this project: I write the code. Claude explains things, reviews my work and writes the parts I hand over to it, which is usually the repetitive stuff I don’t learn much from. For example, I wrote the first few database tables myself to learn the pattern and then handed the rest over once I had it down.

The rest of the process is pretty much how I’d want a team to work:

It’s probably a lot of process for a side project, but it means I can put it down for a week and come back without wondering what on earth I was doing.

It’s also honestly my first time using AI in a side project. I think for me, using AI is helping because this is a side project. I’m working as an iOS Engineer for 8.5 hours during the day before I even sit down to work on this project. If i didn’t at least try and lean into AI to help streamline the process I probably wouldn’t reach the MVP stage.

📍 Where it’s at

I started on 15 October and as of writing there are 18 merged pull requests. So far that’s:

Three screens in dark mode: Welcome, About you filled in with the name Andrew, and the empty Collection tab asking you to add your first piece Where things are right now, in dark mode: Welcome, About you and an empty Collection.

v1 is going to include all four tabs, aftercare, reminders and the share extension for saving ideas. Things like on-device AI suggestions for ideas, search and widgets will come later. There’s also a little Easter egg planned for v1, but I’m going to keep that one quiet for now. 🤫

🔜 What’s next?

Next up is the Collection tab: the photo grid, adding a piece and the body map. That means building a proper photo pipeline, which should make for a good post of its own.

Along the way I’m also planning to write about:

If you’ve got tattoos, I’d love to know how you keep track of yours right now and what you’d want from an app like this. And if there’s a part of the build you’d like me to go deeper on, let me know in the comments. 👇🏻

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