The company says Blocks is simple enough that you can use it even if you have no prior 3D modeling experience. "It's designed to feel more like playing with children's blocks than working with traditional 3D modeling software," Mountain View's announcement reads. The app even gives you various shapes and color palettes to work with, so you won't have to start from scratch, though you will need a Vive controller or an Oculus Touch to be able to use it.
You can let your imagination run wild and create anything you want, but if you're stuck, you can always check out other people's creations on Google's dedicated page for the project. When you're done, you can export the object you created, whether it's a simple watermelon or a complex mecha model, to be part of your VR or AR game/experience. You can also just create an image or a GIF out of it to keep as a remembrance of your efforts or to share with friends on the web. If Blocks sounds like a fun app to play with, even if you have no intention of creating a full VR experience, you can download it now from the Oculus Store or from Steam.