This collection of atoms uses swivel snaps to connect, forming twistable organic molecules that are fun to play with and can be used as a learning tool to demonstrate the shape and movement of organic molecular structures.

See here for assembly and construction video: https://youtu.be/GdgFAmtWh04

The focus of this set is on the four main organic elements (carbon, nitrogen, oxygen and hydrogen), but with a bit of imagination they can be used to represent other atoms as well.

For the sake of simplicity, this set treats double and single covalent bonds the same. This means that a carbon atom with one double and two single bonds uses the same file as a nitrogen with three single bonds because both atoms are bonded with three others and have a similar trigonal pyramidal shape. You may choose to print them in different colours though.

In order for the atoms to fit together properly, bond angles and relative sizes are approximations.

In this set, carbon and nitrogen are the same size: “large”. Oxygen is “medium”. Hydrogen is “small.” For each atom, you will need to print out one of each for the “male” and “female” sides of the hemisphere, and the appropriate number of “swivel snaps.” The files are named for their size (small, medium or large), the number of swivel snaps involved (1, 2, 3 or 4), the orientation of the snaps (tetrahedral, trigonal pyramidal, angular or linear), and the side of hemisphere (male or female).

Here are the files that you will need for each atom:

Carbon (with 4 single bonds): Large 4 Tetrahedral (male and female) and 4 swivel snaps Carbon (with 1 double, 2 single bonds): Large 3 Trigonal Pyramidal (male and female) and 3 swivel snaps Nitrogen (with 3 single bonds): Large 3 Trigonal Pyramidal (male and female) and 3 swivel snaps Nitrogen (with 1 double and 1 single bond): Large 2 Angular (male and female) and 2 swivel snaps Oxygen (with two single bonds): Medium 2 Linear (male and female) and 2 swivel snaps Oxygen (with one double bond): Medium 1, no swivel snaps Hydrogen (with one single bond): Small 1, no swivel snaps

Do not print the "Display Model!"

Be sure to remove all burrs and brims before assembling the pieces. Place the snaps inside the male and female hemispheres and glue them together. CA glue works well.

The tolerance for the snaps is intentionally tight and they will require some force to connect the first few times. After snapping on and off a few times, any imperfections in the interfacing surfaces will be smoothed out and the snaps should remain snug and reliable. If this doesn't work, use a small file or abrasive to smooth out the snap surfaces. (If the snaps are designed to be easy to connect right off the printer, they quickly become loose and non-functional.)