The master piece of this rig is the device to fix it in the hoisting hook of any crane: telescopic, revolving, gantry crane.
It is a stainless steel strip, 35 mm wide and 2mm thick, bent as a loop. The loop can be adjusted or changed to another one to fit the crane hook. It is locked with a Ø 8 mm screw.
It is important that the rig is locked in the hook. Even if moves are usually smooth, an unexpected shock or some kinds of vibration may occur any time.

Under this essential link, any usual kap rig can be fixed.

However, as there is no weight limit, It is worthy to have an heavier rig and fit more accessories and bigger batteries.

The one displayed here has been designed to support reflex camera and have additional flashes for workshop photography, so it is a double floor rig. The frame is made of aluminum sections. It weights 1.3 kg without any camera or device.
The rotational electric device has been dismounted, as it is also the BBQ rotisserie motor. Because the inertia is much larger than for light kap rig, the rotational device has to be robust.
The white box near the camera is a ring bell radio receiver that trigger the camera.

In fact, when there is not enough load, the hook can rotate endlessly and slowly on its axis bearings.

Outside, a large wind vane is helpful and necessary to maintain one direction as sometimes the wind can rotate the rig like a wind mill.