3D Printed Electronic Enclosure

Making the enclosure for an electronic project is not glamorous, but it is super helpful to hide the horrible cable management keep things in place. Getting it right can be tricky though, especially if you are in a hurry. So I’ve made this 3D printable enclosure which can be quickly customized to fit your project.

Using SOL75, an online customizer you can input your board dimensions and download the STL file to print. If you only need the box, that’s it. The rest of this instructable will explain the design choices I’ve made, so that if you want to improve it, you’ll be able to avoid some of the mistakes I’ve made!

3D printer, bolts and nuts

A big challenge is to figure out which requirements make more sense. You can specify the dimension of a box in a lot of ways (like internal size + thickness of the walls, internal size + external size, etc…), so when choosing among different options I try to keep in mind the function of the object.

In this case, the enclosure is built around the electronic board, so it makes sense to start from the board dimensions (like board thickness). The goal is to hold the board, which is likely to have some holes at its corners. Therefore the spacing between the holes and the holes diameters, are the main requirements to design for.

I got carried away and I’ve added quite a few extra parameters, like clearances above and below the board, maximum size for the walls (if you need your project to fit inside a specific space), etc. You can just leave the default values, but if you need them, they can be quite handy.

The first design decision is how to secure the board in place. I toyed with the idea of using some rails in which the board could slide in from the side, but that would require two entire sides of the board without components sticking out. In the end, I decided to use a rectangular hole pattern, since most boards are already designed with one. Four columns protrude from the floor of the enclosure and support the board from below. The question is, how do you secure the bolts when you don’t have access to the back of the board?

My first attempt was to use a nut inserted into the material. It looked promising, but the supporting columns were quite thick (since they had to host the nut) and so they took up a large footprint of the board. Finally, trapping the nut in the material requires careful planning to avoid impossible-to-print overhangs.

So I’ve discarded the first method and chose to have the bolts poke through the bottom of the enclosure. Now the column can be a lot thinner, it is easier to place the nuts and you can easily mount the enclosure + board on some other panel using longer bolts. However, do keep in mind that if you don’t have a proper insulating layer, the bolts may act as a bridge between your board and the outside.

To secure the lid in place I’ve used compliant latches; slender beams with a wedge feature at the end. Since they are very thin, they can easily bend to allow the matching features to lock together quite firmly.

They are my preferred choice because they allow you to open the lid without any tool and can be printed with the enclosure, so no extra parts needed!

For more heavy duty applications however, you might want to use bolts. The overall enclosure will be larger, and printing is not as easy, but it's totally doable. To be able to print the hole suspended in mid-air, I’ve used a sacrificial layer. The idea is that the first layer will be a full rectangle, all printed in mid-air with bridging. The layers above that will have the correct geometry. Then you just have to puncture the sacrificial layer and clean up the edges a bit.

Although a box is a very simple project, it can be a lot of fun to come up with different ways to solve each design challenge. If you have suggestions on how to improve this project, or come up with a better way to solve the issues above, let me know!

If you want to customize your electronic enclosure, here is SOL75, the online customizer I made.