This upgrade is using magnets to connect the cranes to the base. The magnets gives plenty of stability to the crane arm. They are self-centering and rotates with a pleasent amount of resistance. The cranes can easily be removed or slid to the next position.

You can also upgrade the original design by cutting the peg from the crane bases and gluing magnets directly to the base board.

I used cheap disc magnets N52 20x2mm from eBay. Their actual size is measured to 19.5x1.7 mm.

Magnet_Base.stl is made with 19.8 mm holes to fit these magnets. Magnet_Base_Larger_Holes.stl is made with 20.5 mm holes to fit slightly larger magnets. Both Magnet_Base.stl and Magnet_Base_Larger_Holes.stl has a slightly larger outer contour and are a bit thiner than the original. Size now: 185 mm x 5.5 mm Magnet_Crane_Base_with_Handle.stl has a bit larger base and a flat bottom. It also has a smaller hole for the vertical crane arm to fit better.

Warning: If you are working with magnetic sensitive electronics, this upgrade will obviously not be suitable.