Straw Geodesic Models
On this page we will explain step by step how to make a geodesic dome model out of straws. Our model will be a 3v, 5/9 (we explain that boring stuff further down the page).
Our model will be 50cm or approximately 20 inches in diameter (wide).
You need two basic construction materials: straws and paper brads. Straws can be purchased almost anywhere. Paper brads are found at your stationery.
Jumbo straws
Paper brads. 1/2 inch length are recommended.
We recommend using jumbo straws (203mm wide) like those in the image above because they are thicker and stronger than regular straws, and it is simpler to make holes in them. Brads for this project should be ½ inch. You can use a longer size but it does not look as nice.
Dome diagram
This is the assembly diagram for a 3v 5/9 dome. You should print this diagram for reference. The letters identify the pattern which is repeated 5 times to form a geodesic dome. For simplicity we will assemble this exact same dome following different assembly steps.
Okay, now you have your straws and your brads. Now we need to cut our straws, which we will now refer to as “struts”.
30 X A struts: 8.25cm (or 3 1/4 inches) long
35 X B struts : 9.6cm (3 7/8) long
80 X C struts : 10.5cm (or 4 1/8 inches) long
20 X D struts : 11cm (or 4 3/8 inches) long
We need a total of 165 struts.
How to cut a lot of straws for your dome model
To speed up the cutting of 4 different lengths, we suggest that you use a paper cutter like those found in libraries and offices. They usually have a guide that will keep all the straw strut lined up. Another alternative is to make your own from a regular kitchen platform.
However you cut your struts, it starts with a single and exact one which will be used as a template for all others. We need four different lengths so we will have four different templates.
Making holes in the struts
Once all your straw struts are cut, holes need to be made at each end of each strut. There are 165 struts which means you need to make 330 holes. This seems like a lot but it can be done rather quickly. Use a regular handheld hole punch that makes holes 6mm or 1/4 inch wide.
Luckily for us we do not need extreme precision to make the holes. Align the edge of the punch to the straw, the hole made will be exactly where it should be. So no calculations required: simply line up straw and punch.
Make sure your holes line up! When looking at any strut your holes should be on the same plane.
NOTE: you will notice the hole is much larger than the brad pins. This is intentional: because this is a model of a geodesic dome and it is difficult to attain precision, especially with straws, the extra space of each hole helps compensate for possible errors. In other words we simplified the dome model so you can make it more easily and faster.
Assembly
Now that all your straws are cut and have holes, we cab begin assembly.
Step 1: DO THIS 6 TIMES
Take 5 struts and insert a paper brad through each one as in the picture, then add 5 B struts around the start shape
Step 2: DO THIS 6 TIMES
At each tip of the star shape add 2 C struts. When done, attach the C struts together as shown in the picture.
Step 3: DO THIS 5 TIMES
Between each C tip, attach a D strut, except for one (only attach 4 D struts).
You should now have 5 identical dome sections that look as below and another without any D struts:
The top piece of the dome
Step 4:
Attach each section in the following manner:
Note that some brads will need to be removed. When assembling sections together, some brads are no longer necessary.
When looking from the top, your dome should look like below. The missing piece is the one you assembled earlier (without the D struts).
Step 5
The only struts left are for the base of the dome. Hint: almost all the missing struts are C struts except for five (5) B struts.
Assembly at the base of the dome. To line up the base to the structure you just assembled, refer to the assembly diagram at the top of this page.
The finished product
What does 3v, 5/9 mean?
This refers to the frequency of a geodesic structure. Every geodesic dome is identified by its frequency, or number of triangles used to make it. The more triangles, the higher the frequency is. This also means there will be more struts used to make the dome.
What does 5/9 mean? 5/9 tells us that the dome we will build will be 5/9 of a full sphere, therefore more than one half of a sphere.
Final note
You can make any type and size of geodesic dome model using straws or similar materials. Remember that for any strut length of any model we added 1cm to each strut so that holes can be made.
