Tillandsia (or air plants) are perhaps best known for being low-maintenance plants you can place inside a terrarium as they don’t need soil to grow. But if you’re tired of seeing miniature xeriscaped scenes inside what look like miniature greenhouses, here are a few ways to think outside the glass box. 1. Geometric mobile: Brass Himmeli Prism from Hruskaa, Email for price. Or, you can make your own mobile (inspired by the Himmeli) with some string and a handful of straws. 2.