DIY vs Buy Meeting Room Display: The Honest Comparison · ...

Every few months on r/sysadmin or Hacker News, someone posts a beautiful build log of a meeting room display they made from a Raspberry Pi, a salvaged 7 inch screen and a weekend's work. They are proud of it. They should be. And every few months we get a support email from someone six weeks later asking how to migrate from "the thing I built that broke when the WiFi cert rotated".

This post is the honest decision tree. When to build your own. When to buy. What each option costs over a year and over five. And the bit of the build that nobody warns you about.

What "DIY" actually means in this space

People mean two different things by DIY meeting room display.

DIY hardware. Sourcing the parts (Raspberry Pi, screen, case, mount, power) and assembling them yourself. Either matched with off-the-shelf software, or paired with a script you wrote.
DIY software. Buying finished hardware (an iPad, an Android tablet, a TRMNL) and writing the software layer that pulls the calendar and renders the screen.

The first one is the route that goes wrong most often. The second is usually fine. We will come back to that.

The realistic cost of DIY, for one room

If you go all the way and build your own, here is a typical bill of materials for a single room display.

Raspberry Pi Zero 2 W: USD 15
7 to 8 inch screen (HDMI or Pi camera ribbon): USD 60 to USD 120
Case, mount, USB cable, micro SD card: USD 40
Power supply (or PoE adapter): USD 25 to USD 60
Time to build: half a day for the first one, two hours for each subsequent one
Time to write the calendar sync script: anywhere from one day to one week, depending on your familiarity with Microsoft Graph or the Google Calendar API

Total: roughly USD 150 to USD 250 in parts per room, plus 1 to 5 days of one person's time across the whole rollout. For 5 rooms, that is around USD 1,000 in parts and a week of engineering.

Compare that to a TRMNL plus Lobby setup at USD 129 to USD 199 per room (one-off), USD 0 to USD 30 per month for software, and 10 minutes of setup per room. For 5 rooms, that is around USD 800 in hardware, USD 30 per month, and an afternoon of work. Covered in the TRMNL meeting room display post.

For a single room, DIY and buy are roughly comparable on hardware cost. The difference is the time, and the ongoing maintenance.

The bit nobody warns you about

Hardware is the easy part. The thing that gets DIY meeting room displays the next time, every time, is one of the following.

OAuth token rotation. Your script holds a token to read the calendar. Tokens expire. Refresh tokens have edge cases. When your script silently stops syncing on a Sunday morning, you get to spend Monday morning debugging it.
The certificate the corporate WiFi requires changes. The Pi was working fine. The cert rotates. Now it cannot reach the calendar. You find out when someone walks past a display still showing yesterday's meetings.
The screen blanks itself. The default Pi config will turn off the screen after 10 minutes. You have to disable that. There are at least three ways to do it. Two of them stop working after a Raspberry Pi OS upgrade.
You leave the company. The display worked when you set it up. Nobody else knows how. Six months in, three displays are dark and the office manager is sending screenshots to the new hire who has never seen the code.

None of these are insurmountable. All of them are the kind of thing that turns a USD 200 capital saving into a recurring soft cost across multiple people's calendars.

When DIY is actually the right call

There are real cases where building your own is correct. They are narrower than people think.

You have one room and an internal engineering team that enjoys this kind of thing. One room is the right scope for a fun project. Five rooms is when it stops being fun.
You have unusual hardware constraints. No WiFi, a specific screen size, integration with a security system that no off-the-shelf vendor supports.
You have a strict requirement to self-host the entire stack. Some regulated industries genuinely cannot send room booking data to a third-party SaaS. In that case, build it, but build it properly with a real engineering team.
You want it as a learning project. Genuinely fine. Build one. Just do not roll it out to ten rooms and call it a deployment.

The middle path: buy the hardware, choose your software

The interesting option is the one most people miss. Buy the hardware. Decide on the software later. This is exactly what open-source hardware like TRMNL gives you.

You get a finished, low-power, battery-driven e-ink display for USD 129 to USD 199.
You can run Lobby on it today.
If you change your mind, you can run a different platform tomorrow.
If you really want to, you can point the device at your own server and render anything you like. The protocol is just "fetch a PNG from this URL on a schedule".

You get most of the upside of DIY (no lock-in, the option to write your own software) without the downside (the hardware is finished, the firmware is maintained for you).

The "use what you already have" version

If you have a spare iPad or Android tablet in a drawer, that is also a perfectly reasonable starting point. The hardware is sunk cost. You just need software that runs on it.

Both posts cover the three approaches and the scheduling-off-overnight problem nobody warns you about.

The five-year total cost of ownership picture

For 10 rooms, over five years, the picture roughly looks like this. All in USD, rounded.

Full DIY (Pi plus screen plus self-written software): USD 2,000 in parts, plus 1 to 2 weeks of engineering up front, plus an average of 1 to 2 hours per month of maintenance across the fleet. Roughly USD 2,000 + USD 9,600 of soft engineering cost at USD 80 per hour over 5 years. Around USD 11,000 total.
TRMNL plus Lobby: USD 1,500 in hardware, USD 1,800 over 5 years on the paid plan, basically zero maintenance. Around USD 3,300 total.
Joan or Robin: USD 6,000 in hardware, USD 5,000 to USD 10,000 over 5 years in software depending on plan. Around USD 11,000 to USD 16,000 total.
BYOD tablet plus Lobby: Zero hardware (assuming you have tablets), USD 1,800 over 5 years on the paid plan. Around USD 1,800 total. The lowest-cost option.

The cheapest option, by a margin, is "use the tablets you have, plus a SaaS that does the calendar work for you". DIY is the most expensive route once you cost in the engineering time honestly.

TL;DR

Full DIY meeting room displays cost more than they look like they should once you include OAuth, certificates, the inevitable WiFi config change, and the bus factor of the person who built it. Build one if you have one room and a curious team, or if you have an unusual constraint that off-the-shelf cannot meet. For everyone else, the right answer is either "use a BYOD tablet plus a SaaS like Lobby" or "buy open-source hardware like TRMNL plus a SaaS that runs on it". Both come in cheaper than DIY at any rollout size above two rooms.

DIY vs Buy: Should You Build Your Own Meeting Room Display?