This is the Gravity Assist Mechanical Simulator. Complete, illustrated instructions are provided for building this device and running gravity assist simulations.
A bearing ball (BB) is launched from the ramp at middle-right, and as it rolls upward and towards the left on the inclined glass, it encounters a revolving magnetic "Jupiter," which can boost the BB higher up the glass surface.
A 12-inch-square concrete brick serves as a mass to support the hole-punched steel strap suspending the DC motor and the "Jupiter wheel" slightly above (and parallel to) the inclined glass tabletop surface.
Note the aluminum bar inserted between the strap and the brick. This provides an easy way to adjust the motor height. The cutout paper Jupiter image can be seen on the right side of the "Jupiter wheel" acrylic disk, hiding a powerful flat magnet mounted to the disk.
The motor has a cutout image of the Sun to illustrate that Jupiter is revolving around the Sun (counter-clockwise). The paper clamp on the edge of the Jupiter wheel serves to trip the BB release gate (a carved chopstick) as it comes around. The right end of the release gate can be seen resting on the BB ramp, where it restrains the BB before launch (BB not in place in the image).