Smartphone-based VR headsets are all the rage, from heavy plastic units to lightweight cardboard devices. But what if you’re on a budget, or need something quicker than the mailman can deliver?

The smart answer is to make your own Google Cardboard VR goggles. All you need is some card, a design, lenses, and a means to secure your phone in the goggles. Here’s everything you need to know about making your own Google Cardboard VR headset.

What Is Google Cardboard?

Google Cardboard is the simplified VR headset kit from Google. It is essentially a cardboard vr box, equipped with 45mm focal length lenses. Also included are hook-and-loop fastenings for securing your phone, a magnet, and a rubber band. Compatible with Android and iOS devices, Google Cardboard also includes an NFC tag, for fast launching of VR apps.

Since its launch, many competitors have unveiled their own takes on Google Cardboard. Smartphone-based VR has become so popular, meanwhile, that plastic headsets have become widely available. Some are even cheaper than Google Cardboard.

You can buy anย official Google Cardboard VR headset online—it’s inexpensive, as you can see—but building your own is simple and relatively quick.