Sigma Bond type 1
This is the module used for a signle bond between two atoms. In reality, atoms are able to rotate with this sort of bond, but in these origami recreations, not so much, so I've come up with two different ways of representing the single sigma bond between two atoms. If the rotational orientation between your two atoms don't matter, or if it's otherwise fine for the atoms to be rotated about 60° with respect to each other, use this bond.
If the Atoms need to not be rotated with respect to each other - necessary for carbon rings - or if it's the sigma bond of a double or tripple bond, use the type 2 sigma bond modules.
If you've built your modules and need to know how to put them all together, head over to the assembly page.
Sigma Bond 1
This is the first sigma bond unit. Three of these attach two atoms point to point, rotated about 60° with respect to each other. Three of these units are used to bond two atoms together.
Starting with a square which is the same size as the ones used for the atom units, cut the square into 1x4 strips.
Fold in half the long way
Fold in half the short way
With the open edges facing towards you, mountain fold the closed corner as shown. This forms a point that will go into a pocket on the atom unit to hold the two together.
Step 3 Complete
This is what you should end up with. Flip it around so the sharp point is to the upper left.
Valley Fold only the top two layers. The long edge should line up with the mountain folded corner from step 3.
Valley fold so that the upper right corner meets the sharp point.
Valley fold the upper left corner down to where it meets the center point where all those layers intersect. This forms one of the points that will go into a pocket on the atom unit of the other atom.
Valley fold the lower right corner to the top edge of that branch of the unit. This forms a second point that will go into a pocket on the atom unit of the other atom.
This is the completed unit. Stretch out the zig-zag folded branch a bit.
With the zig-zag branch streched out, you can see all the points that go into the various pockets in each atom. Fold two more of these for each of the type 1 sigma bonds.
Once completed, visit the assembly page to put it all together.