Geomag Forum

Here is the step by step construction of my giant 585-hourglass and the 297-Water Drop (click on the photos to enlarge).

[Edit]: Warning! Deprecated method. You will find a faster and more efficient way to build hourglass bulbs here.
This old construction method should be replaced by the one mentioned above.
Once you've built your 2 bulbs, you can resume here in this thread (from the second picture).

The set of rods (294) to build one of the two bulbs:
As I changed the color scheme at the very end I don't have quite the right number of color rods here. But that's not a big deal, it doesn't change anything at the construction stages.

First, build a simple Lobel frame with a triangle as central polygon.

On this kind of Lobel frame if you look closely you will see a straight line of rods in alignment with each vertex of the central polygon. Which here is a triangle.

Stop when you reached 5 successive rows of triangles around the central triangle.
In an attempt to save time I tried to apply my final color scheme at this point.
So I replaced some silver rods with colored ones. But at the very end, that's not the one I kept. Never mind. Nice try .
In fact, by reshaping the Lobel frame a little, you realize that it is a simple tetrahedral pyramid. But for what we want to do, we have to keep this rounded shape.

You have to start shortening the rows of triangles to close the construction and get the bulb shape. To do so, you have to form a hemisphere. The construction scheme will therefore change from now on.
As you can see you get 6 outward facing pentagonal pyramids at the end of this sequence.


You have to reverse them and turn them inward. Once this is done you observe that the pentagons are separated vertex to vertex by 1 rod. The corresponding model of sphere is this truncated icosahedron (more commonly known as a soccer ball ). This is how you have to close the bulb.

Final color scheme on the 4th photo

Now that you have completed your first bulb, make a second one :
All you have to do is stack them, remembering to remove the upper triangle (3 rods and 3 spheres) from one of the two.
And tada! You have your real giant 585-hourglass.

Wau, i must built IT.

Thank you very much for the inspiration

Very nice Tychi! And of course again super compliments to Eric.

I feel like a jerk for not having built it yet..