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Background

I want to make simplistic models of atomic structures using spheres (overview). Each model consists of maximum 10 spheres that have the same diameter. Normally I use ping pong balls or balls made from styrofoam as they are easily available and have almost no weight. Here is a rendered sphere arrangement as an example:

Image source

Requirements

I want to create sphere structures that can easily be constructed and modified. After construction the spheres should stay in their positions but it should also be possible to easily change the sphere positions. It should be possible to attach spheres in any orientation and not only at predefined positions. As spheres should allow easy handling with your hands and be visible for demonstration their optimal diameter is in the range of 3 to 6cm. The shape shall be spheres, no deformed or bevelled variants. Spheres must be touching, therefore I cannot use spoke models that are sold as molecule construction kits, e.g.:

Image Source

Questions

How can I easily attach and detach the spheres? Are magnetic balls suitable for my purpose?

Possible methods

keeping together with your own hands:

This is the easiest way but your hands cannot hold not more than 5 spheres in defined positions. Permanent fixation is not possible.

gluing spheres:

This process is not reversible and it takes long time until the glue hardens.

spheres fully consisting of magnetic material:

I have not tested them. Will they work? They attract each other and might allow only limited configurations. For demonstration spheres with at least 3cm diameter are needed. Sphere arrangements might be not stable under their own weight. They are costly and before I buy them I would know if the spheres arrest in any position.

partially magnetic spheres:

They are sold under the brand Snatoms. They can easily and reversibly be connected. However, they are not suitable as they are bevelled and allow connection only at defined positions.

Related question

I am also interested in digital models and looking for a program that allows easy creation of touching spheres. See this post.

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Toothpicks and Styrofoam Spheres. Use the toothpicks to both symbolize the bonds and hold the spheres in appropriate alignment with each other. Since you want the spheres to touch, use slightly larger styrofoam spheres so that a half a toothpick can be hidden inside each conjoined spheres. (...or break your toothpicks in half).

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  • Velcro-covered spheres

    • Since children's games making use of Velcro balls can be found in many toy stores, a cheap option would be to start with buying a few of these balls (e.g.), find some additional self-adhesive Velcro straps or tape, and attach the side with the opposite functionality (hook or loop) to the balls. This will allow for a lot of configurational freedom.

    • Another option in the same vein, which will give you a little more leeway in the visual appearance of the balls, is to attach both sides of the tape, or Velcro pads, to any kind of sphere you want.
      This is especially preferable if you want the spheres to be of a harder/rigid rather than soft material.

  • There actually exists another type of toy that you wouldn't have to customize, called 'Bunchems!'. They seem to work on a larger scale version of the hook-and-loop principle, and won't require additional tinkering (don't let any children play with them, though [links to a video, but you only have to see the cover to get the idea] :).

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You could also 3D print spheres in different colors (representing different atoms) with regular cutouts that serve as sockets for connetors.

One example is this honeycomb sphere:

enter image description here

If you print fitting hexagonal collums, you can connect several spheres. Technically it won't allow any orientation, but I think it's close enough to be practical.

One aspect you need to keep in mind is the structural integrity of different 3D printing technologies. Cheap filament extrusion prints are very instable along the planes of the print. If you print the connectors standing straight up like collums, they are very likely to snap. You should print them in a slanting position to give them more stability.

Resin prints, on the other hand, are much more stable, but also more expensive. It might even be worth buying hexagonal wood dowels from a home construction store and adjusting the size of the 3D printed spheres to the size of the dowels.

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