Shadow rigs are a certian type of rig style that mixes perspective and 3D shading to create a 3D-ish rig. (yes I named it cause no one else did) Inside this project is a little template I made. If you want more "3D-ness" use more directions. The 3D-ish shading does not effect how 3D it appears, only how much shading there is to it, which only makes it feel 3D instead of 2D. By the way, if there are simple shapes, you don't need perspectives, but you could use a 3D grid as reference.)
GLITCH (what this rig is, not the idea)