Valve has released 3D files to help people build mods and accessories for its new Index virtual reality headset. The gaming company posted high- and low-resolution models — along with other documentation — on GitHub under a Creative Commons license. Anybody can download and use the files to design their own creations, but they can’t sell anything without getting clearance from Valve first.

The Index headset, which started shipping last week, is a high-end VR system based on Valve’s SteamVR platform. Valve designed the Index to appeal to modders, adding a USB port for them in a small compartment called the Frunk or “front trunk.” Now, the company is offering some more detail about how this tinkering should work, including notes on where the Index’s sensors are located so people can attach extra hardware without damaging tracking quality.

You can find computer-aided design (CAD) models of the Lighthouse base stations, the headset itself, and the motion controllers formerly known as “Knuckles.” Valve has also released a few examples of simple accessories. The “booster” grip, for instance, can help some users’ hands rest more easily on the controller stock. You could also design your own padded face mask to replace the one that’s included with the headset.

Valve has released these kinds of files before. It made the Steam Controller’s CAD files available in 2016, urging buyers to customize the PC gamepad. Results included custom cosmetic mods and snap-on joysticks to replace the idiosyncratic trackpads — something you can also 3D-print for the Vive SteamVR headset.

VR headset modding isn’t new either. The Razer-backed, open-source OSVR project was even aimed at helping developers test hardware and software with a cheap VR headset. That headset was basically a development kit, though, while the $999 Index is a full-fledged (albeit niche) consumer product. So non-professional designers might want to mod their headsets like they would a gaming PC — even if it’s just something cosmetic, like making a custom front plate for the headset.