STEM at Home: 10 Creative Projects Combining Home Assistant, ESP32 and 3D Printing

World STEM Day is a good opportunity to look at the technology in our homes from a slightly different perspective.

A smart home is not only about buying sensors, switches and smart appliances. It can also be about understanding how technology works, identifying problems around you and building your own solutions.

This is where platforms such as Home Assistant become particularly interesting.

Combine Home Assistant with an affordable ESP32 development board, and you have a small platform for building your own connected sensors and controllers. Add a 3D printer, and you can also create the physical enclosure, mounting system or control panel needed to turn a small electronics project into something that belongs in your home.

You do not need to be an electronics engineer to explore these ideas. Some projects can be simple experiments, while others can become surprisingly advanced.

The important part is not necessarily building something complicated.

It is learning to look at your home and ask:

“Could I build a better solution for this?”

Here are ten ideas that combine Home Assistant, ESP32 and 3D printing.

1. Build Your Own Multi-Sensor

One of the most obvious ESP32 projects is also one of the most flexible: build your own environmental sensor.

An ESP32 can be combined with different sensors to measure things such as:

• Temperature
• Humidity
• Air pressure
• CO₂
• VOCs
• Light levels
• Motion
• Occupancy

The exact combination depends on what you want to monitor.

A 3D printer then makes it possible to create an enclosure specifically designed for the sensors you have chosen. Instead of adapting your project to a generic plastic box, you can design the box around the electronics.

The real value comes when Home Assistant starts using the data.

Temperature measurements can influence heating. Humidity can trigger ventilation. CO₂ levels can indicate when a room needs more fresh air. Light measurements can be used to control lighting automatically.

A small ESP32 project can therefore become part of a much larger automation system.

2. Create Your Own Presence Sensor

Motion detection and presence detection are not quite the same thing.

A traditional motion sensor may detect someone walking into a room, but it may not know that the person is still sitting quietly on the sofa.

This makes presence detection an interesting area for DIY projects.

An ESP32 combined with a suitable presence sensor, such as a mmWave radar module, can become the foundation of a custom presence sensor.

The 3D-printed enclosure could be designed for a particular location:

• Mounted on a wall
• Installed in the ceiling
• Hidden on a shelf
• Integrated into another device

Home Assistant can then use the presence information to control lighting, heating, music, ventilation or other devices.

The interesting part is not simply detecting whether someone is home.

It is understanding whether someone is actually using a particular room.

3. Build a Physical Home Assistant Dashboard

Most Home Assistant dashboards are digital. They live on a phone, tablet, computer or wall-mounted display.

But what if you built a much smaller dedicated display?

An ESP32 with a small screen could become a physical information panel showing the most important information in your home.

Depending on the display and project, it could show:

• Indoor temperature
• Outdoor temperature
• Current electricity consumption
• Solar production
• Battery state of charge
• Energy price
• Weather conditions
• Home or alarm status

A 3D printer could be used to create a custom enclosure or wall mount.

The result would not necessarily replace a full Home Assistant dashboard. Instead, it could provide a quick glance at the information you care about most.

Sometimes a small dedicated display is more useful than opening an app.

4. Design Your Own Smart Button

Smart buttons are another excellent example of a simple idea that can become surprisingly powerful.

Instead of having a generic button that performs one action, you could design a physical control specifically for your home.

Imagine a 3D-printed button labelled:

Good Night

Pressing it could trigger a Home Assistant script that:

• Turns off the lights
• Locks the doors
• Activates the alarm
• Adjusts the heating
• Turns off unnecessary devices
• Checks whether windows are open

The physical button itself could be built around an ESP32 or another suitable microcontroller.

The interesting part is that the button is no longer just a button.

It becomes a physical interface to your automation system.

This is one of the strengths of Home Assistant: the physical device and the automation logic do not have to come from the same manufacturer.

5. Build a Smart Plant Monitor

Plants are another fun area for experimentation.

An ESP32 combined with a soil moisture sensor can provide information that is otherwise difficult to monitor.

You could potentially track:

• Soil moisture
• Temperature
• Light levels
• Humidity

Home Assistant could then notify you when a plant needs attention.

A more advanced setup could even compare moisture levels over time and help you understand how quickly a particular plant dries out.

The 3D-printed part could be as simple as a small enclosure for the electronics or a custom holder that keeps the sensor in the correct position.

The goal is not necessarily to create a fully automated watering system.

It could simply be about learning how sensors, data and automation work together.

And if Home Assistant eventually sends a notification saying:

“The basil could use some water.”

That is probably a successful project.

6. Create a Smart Mailbox

Here is an example of a project that solves a very specific problem.

Did someone put something in the mailbox?

An ESP32 combined with a suitable sensor could potentially detect when the mailbox is opened.

Home Assistant could then send a notification:

📬 You’ve got mail!

The exact implementation could vary depending on the mailbox and installation.

A magnetic contact could detect the door opening. A vibration sensor could detect movement. Another sensor could potentially detect when something has been placed inside.

The 3D printer could be used to create a custom sensor mount that fits the mailbox.

This is a good example of where DIY smart home projects can be particularly useful.

There may not be a perfect commercial product for every small problem.

But with Home Assistant, an ESP32 and a little creativity, you can sometimes build exactly what you need.

7. Build a Custom Energy Display

Energy monitoring is one of the areas where Home Assistant can become particularly powerful.

If your home already has energy sensors, electricity price data or solar production information, you could create a dedicated display showing the information that matters most to you.

For example:

Current Power: 2.4 kW
Solar Production: 1.8 kW
Battery: 82%
Energy Price: 0.72 NOK/kWh

An ESP32-based display could sit in the kitchen, hallway or utility room.

A 3D-printed enclosure could turn it into a small dedicated energy station.

The project could also become more interactive.

Perhaps a button could cycle between different screens:

• Current consumption
• Today’s energy usage
• Solar production
• Battery status
• Electricity price

This is a great example of how a DIY project can transform Home Assistant data into something tangible.

Instead of opening an app to check your energy usage, the information is simply there.

8. Make a Smart Button Box

A single smart button is useful.

A box with several buttons can become a completely different type of interface.

Imagine a small 3D-printed control panel with four buttons:

HOME
AWAY
NIGHT
MOVIE

Each button could trigger a different Home Assistant scene or script.

The Movie button could dim the lights and turn on the television.

The Night button could prepare the entire house for bedtime.

The Away button could turn off unnecessary equipment and activate security-related automations.

The physical design is completely up to you.

You could make it minimalistic and Scandinavian, industrial and technical, or design it to match the interior of your home.

This is where 3D printing becomes more than just a way to make boxes.

It allows you to design the interface itself.

9. Build a Sensor for a Very Specific Problem

Perhaps the most interesting STEM lesson is this:

Start with a problem, not a product.

Instead of asking:

“What smart device should I buy?”

Ask:

“What problem do I have that technology could solve?”

Maybe you want to know if:

• A freezer door has been left open
• A storage room door has been opened
• Water is collecting under a washing machine
• A cupboard is getting too warm
• A pump is vibrating differently than usual
• A mailbox has been opened
• A particular device is running when it should not be

There are countless small problems around a home that do not necessarily have a ready-made smart product.

This is where ESP32 projects can become really interesting.

You can choose the sensor that matches the problem, connect it to Home Assistant and build an automation around the information.

The 3D printer can then create the physical solution needed to install the sensor exactly where it belongs.

This is perhaps the purest example of the STEM mindset.

Observe a problem.

Form an idea.

Build something.

Test it.

Improve it.

10. Build Your Own Complete Smart Home Device

The ultimate project is to combine all three technologies.

ESP32 provides the hardware and sensor input.

Home Assistant provides the intelligence and automation.

3D printing provides the physical design.

Imagine a custom sensor that detects when a window is open.

The ESP32 sends the state to Home Assistant.

Home Assistant checks:

• Is anyone home?
• Is the heating running?
• What is the outdoor temperature?
• How long has the window been open?

If the window remains open for five minutes while heating is running, Home Assistant could send a notification or temporarily adjust the heating in that room.

The individual components are not necessarily complicated.

The interesting part is the system created by connecting them together.

This is where a simple electronics project becomes a smart home project.

The Best Project May Be the Smallest One

When people think about DIY smart home projects, it is easy to imagine complex systems with dozens of sensors, custom circuit boards and elaborate automations.

But the most useful project may be much smaller.

Perhaps it is a sensor that solves one problem that has annoyed you for years.

Perhaps it is a physical button that saves you ten taps on your phone every evening.

Perhaps it is a small display that shows the one piece of information you constantly want to know.

The combination of Home Assistant, ESP32 and 3D printing makes these projects accessible because each technology solves a different part of the puzzle.

ESP32 gives you flexibility.

Home Assistant gives you intelligence.

3D printing gives you freedom of design.

Together, they create a platform for experimentation.

Where Should You Start?

If you are new to this kind of project, you do not need to start by designing a complicated device.

Start by looking around your home.

Find one small problem.

Ask whether a sensor could provide useful information about it.

Then ask what Home Assistant could do with that information.

If you cannot find a suitable commercial device, an ESP32 might provide the missing piece.

And if you need a custom enclosure, mount or control panel, a 3D printer can help turn the electronics into something practical.

The important thing is to experiment.

You might build something that works perfectly.

You might build something that does not work at all.

You might discover that buying an existing product would have been easier.

That is all part of the process.

The most interesting smart home projects are not necessarily the most complicated ones.

Sometimes the best project is a small sensor that solves one very specific problem that no commercial product was designed to solve.

And that is perhaps the perfect way to celebrate STEM Day: being curious, experimenting with technology and building something simply because you want to find out if you can.