This is a companion post to the Make magazine’s Weekend Projects Podcast

I love the look of domes and geometric spheres, and this week we are going to make some out of things that you might find around the house or at a picnic. Making geometric speres is fun, and you end up with something impressive that you can hang up or display.

If these projects are interesting to you, make sure to check out the article, “Building Tensegrity Models,” by William Gurstelle in MAKE: Volume 06. Tensegrity is the art of building geometric shapes with rods suspended in mid air by string.

The projects presented here are all based on a 20-sided figure called an icosahedron, which is made out of equilateral triangles. Equilateral means that the sides of the triangle are all the same length. You can download a pdf of these projects to print out: Link

Paper Plate Icosohedron

Step 1: Make the Template

For this project, keep an eye out for paper plates and acquire 20 of them. Make an equilateral triangle template by folding it in half vertically and horizontally to mark the center of the plate, and then use a protractor to measure and mark out 120, 240, and 360 degrees. Fold the edges to the center, and you’ve got your template ready to go.

Step 2: Fold a Total of 20 Plates

Trace the triangle onto 19 other plates and fold them up so that they are all the same. Push down rather strongly with your pen. This makes folding quicker and easier.

Step 3: Assembly

Staple them together and display!

Dixie Sphere

For the Dixie sphere, I must direct you to the instructable page where I found this project. Instructables.com is a great website where anyone can upload instructions for how to make something. Note: Some of the language on this particular page is not suitable for young children.

Giant Inflatable Icosahedron

Step 1: Find a lot of plastic, two rolls of duct tape, scissors, and a ruler. If possible use recycled material.

I used 10’x25′ 4mil plastic used for laying down on the floor before painting. You could use trash bags instead, though. I thought about using Tyvec, but they claim that it is breathable, so I wasn’t sure how well it would hold air.

Step 2: Plan it out.

Lay it all out on the floor. I only laid part of it at a time, since the room I was in was too small to be able to put it all down. Then tape it all together

Step 3: Assemble.

I taped it all together flat first with tape on both sides of the seam. This may have been overkill, and you may be able to get away with just putting tape on one side. It was a little tricky since the plastic didn’t really want to cooperate in the small room. If I ever get ambitious and want to make a bigger inflatable sphere, I’ll need to find a big space to do it in or maybe sneak into a community center.

At home, I filled it with a vacuum by taping the extension to the exhaust port, and at the park, I used a little pump meant to fill up an inflatable bed.

Step 4: Play!

Giant soccer would be the ultimate picnic game. I think to preserve the ball, you’d have to say no hands or feet!

All you need to make an icosohedron is triangles, and you can even use circles like cups to make triangles, so the creative opportunities to use all sorts of materials is ripe with possibilities. Make your own geometric sphere, take a picture of it, and upload it to the Make: Flickr Pool

You can leave a comment on the blog at https://makezine.com/blog or drop me an email at bre@makezine.com.

## 4 thoughts on “Weekend Projects – Picnic Geometry Instructions”

1. PhantomBantantam says:

I too have used that plastic sheeting for something inflatable. It was not so geometrically nice, but I ironed the seems shut, and filled it with helium. It did float, but was fairly small and just a proof of concept.

2. joelanders says:

This reminds me of these huge black bags I’ve seen somewhere that one is supposed to fill with air, seal off, and leave in the sun. Supposedly the sun heats the air in the bag enough so that it rises. I’ve never tried it though. Sounds mischievous… hehehe…

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### Bre Pettis

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