Google is encouraging more people to check out Google Cardboard, the virtual reality platform and headset that connects to a smartphone. Over 500,000 of the devices shipped this year and now VR apps have their own section on the Google Play Store, featuring apps that include musical performances and exotic locations. Now, the tech giant has released an SDK for Android and Unity, so that developers can continue making apps and crafting their own custom headsets.

Currently, the Google Play Store has some 25 featured apps. These apps range from free to a couple of a dollars, and they take viewers to new locations, live concerts, and game scenarios. To get more content like this, Google has released two new SDKs so that developers won’t have to worry about the technical details of getting their apps to work on Cardboard.

The SDKs are comprehensive. “The Android SDK handles everything from lens-distortion correction to head tracking and the rendering for developers who want to write their own OpenGL apps,” TechCrunch reports.

The Unity SDK is integrated with the Android SDK, and it allows developers to start from scratch or build on other Cardboard apps.

Developers can also build on the Google Cardboard viewer. Google released new specs on the viewer so that developers can design their own components accordingly. The new SDK has a calibration feature, so that the apps will be able to adjust the viewer’s base and focal length to the customized viewers.