This part was tricky at first. I did a lot of thinking about this step and finally had to fall back on information from the internet (Don't judge.)
Regardless of how I came to know about any of this I learned a few things about Geodesic domes and spheres and how they are put together. I didn't learn a whole lot and there are large volumes on the subject if you are more interested in that aspect of the instructable.
All of the necessary findings I used can be summed up in this link.
I was not very practical at first in trying to tackle the idea, but this website saved my life and I give full credit to those who made the site. Let me be clear that none
of that is my material. I relied on the site to help me figure out the lengths for the struts I eventually used.
Let me break down the simple jargon you may need to work on a dome, or sphere of your own (this is almost indispensable if you have a team working and don't want to make up all of the verbiage used.)
These are the intersecting points between each group of triangles that make up the shape: essentially, the vertices.
These are the lines that connect the hubs to other hubs.
Clicking on the above linked site will make what I just said very evident.
There are different levels of detail in a Geodesic sphere, and the math can get a bit complicated if you're like me.
To break it down to a simple level was my first priority, so for my sphere I decided to make a 2V shape because 1) it was simpler, and 2) it was cheaper. Since this was my first geodesic build (except for a straw/pipe-cleaner structure) I wanted to use my material effectively and make something that also looked nice.
There are a few things that are good to know when building a 2V geodesic dome or sphere:
There are six
pentagons in a Geodesic dome, in a sphere there are, naturally, twice that many -- two domes connected make a sphere in this case.
There are ten
struts across the bottom of a dome, on a sphere half
of those struts are unneeded on both domes because the pentagons' bottom edges interlock, making the full circle complete (This will explain my use of less material later on down the page.)
Hence for a dome you do not need to make a bottom edge at all, only focus on making the six pentagons.
Finally the letter V in 2V, 3V, 4V and nthV domes and spheres is actually the letter Nu. Though I was originally trying to use Pi to figure out my sphere, with the calculator you can get away with Nu, or less (don't worry - I could even do this; no math skill required.)