This thing is a Lego-based phone camera gimbal, which in my case gives me a chest-mounted, hands-free hiking/climbing camera. The gimbal consists of a double and single Lego axle, reinforced top and bottom with Lego plates. A 20mm Lego tire + hub is press-fit into the chest hook. The double axle + hubs are secured to the phone holder with zip ties or strong thread. Small felt washers sit between all axles and hubs to dampen their swing. The phone holder is matched to my Nexus 4 + case (73mm x 139mm x 12mm). You may need to stretch/shrink the STL to make it work with your device (you may also need to cut recesses for any buttons). The tabs on the sides of the holder are to take rubber-bands (to secure the phone in the holder). UPDATE: Added 'landscape' version of the phone holder.