This 3D model was originally created with Sketchup 6 and then converted to all other 3D formats. Native format is .skp 3dsmax scene is 3ds Max 2016 version, rendered with Vray 3.00 We were instructed to make a shooting rig, which allows you a marble about 20 meter away could shoot. The ground plane should be max. 30 by 30 cm. You could use five or post elastics or a mass of 2 kg. The device had to because of the security to be firing with a trigger mechanism. K.Sharif