to make a gear, create a disc, edge detect it to obtain a circle and then blend it in add mode with a circular splattered square. add a disc in the middle and perspective the whole setup. create a splatter circular for the inner branches of the gear and add a circle on top to link the branches before edge detecting it to bow the angles. perspective the setup and blend it in Max mode with the first one. if you need to rotate a gear in 3D, simply squeeze the setup vertically with a transform before applying the perspective node.
nb: the wheel behind the character is simply several splatter circles using this kind of shape.