Practical 3D prints: A first TinkerCAD project for your 3D printer

Today, we're going to work on a very simple but useful first TinkerCAD project for your 3D printer.

3D printing in action: Creating a mailbox flag to solve a problem

This is the beginning of a series on practical prints for your 3D printer. Lots of people have seen 3D printers in action, but many of the prints are what can best be called novelty prints. They're action figures or statues of gaming miniatures. Practical prints like brackets and basic signs are shown far less often (probably because they're not as photogenic).

ZDNet Recommends

Best 3D printers for business in 2020: Stratasys, MakerBot, Ultimaker, and more

Which 3D printer is right for your business? We've evaluated the offerings of 14 leading printers, all capable of creating 3D objects, but with a wide-range of characteristics.

Read More

But I find 3D printing enormously helpful in solving practical problems. Whether it's adding support to an organizational system to free up desperately needed space, a way to make sure our mail carrier picks up the mail, or a system for remembering what was last fed to the dog when both of us care for him, 3D printing has come to the rescue.

Most of the time, especially for quick-fix projects, I use a free 3D modeling tool called TinkerCAD. It's incredibly simple and easy to use. I also use Fusion 360 for more complex models and SketchUp for woodworking projects. In cases of hybrid projects, I'll sometimes use more than one tool.

In this article and its accompanying video, we're going to use TinkerCAD. Let's get started.

The problem we're solving

The problem statement for this project is very simple. My wife and I wanted our mail carrier to pick up our mail when we put something outgoing in the mailbox. Unfortunately, that wasn't happening. So, when I called my local post office, they said we needed a flag on our mailbox for the mail carrier to pick up our mail.

The solution was 3D printing. Today, I'll show you how to make a very simple magnetic flag for your mailbox. You can apply this to all sorts of things, but in our case, I made it for the mailbox cover.

Editing in TinkerCAD

The project consists of a couple of basic objects. As the video shows, we're going to start by bringing out a box. I'm able to pull on a corner and make it bigger. I'm going to change its height and as you can see in the video, there are handles. There are corner handles, there are center handles. By pulling and pushing on the handles, we're able to create a long rectangle that will form the backbone of the flag.

The entire design consists, then, of one long rectangle. That rectangle is duplicated and shortened. That makes the flag. Then a square is created that's the size of the flag, rotated 45 degrees, and used to cut out the triangle portion of the flag. I know it's a bit confusing, but the video shows it all very clearly.

Earlier, I created a shape that's basically a short cylinder. I named it "workshop magnet" because it's exactly the size of one magnet in a set of 100 magnets I bought a few years ago.

The idea of the predefined shape is that anywhere I put it, TinkerCAD will hollow out a space for the magnet to fit. Once space is hollowed out of the long rectangle for two magnets, we're done. We have a 3D model that we can turn into a practical print.

Sending it to the printer

That's the entire 3D design for this project. All we need to do is select it, export it as an STL file, and send it into Cura to be sliced for printing. Then I sent it to the Ultimaker to print.

And that's it.

So there you go, a very simple mail flag for our mailbox. As you can see, it's just a simple set of TinkerCAD primitives connected and printed out. The result: Our mail is being picked up.

Be sure to explore TinkerCAD. It's simplistic but it's surprisingly powerful at the same time. Stay tuned for more practical prints.

And what about you? Have you made useful things with your 3D printer? If so, let us know in the comments below.

You can follow my day-to-day project updates on social media. Be sure to follow me on Twitter at @DavidGewirtz, on Facebook at, on Instagram at, and on YouTube at