A general rule of thumb for origami design is that long, thin appendages should be allocated on the corners or the edges of the sheet for better efficiency. For spider subjects, most designers would choose to allocate all legs on the edges in an octagon formation, since using the corners would lead to an asymmetric layout.

Such a formation, however, tends to leave a relatively large empty space (comparing to the leg length) in the center. For spiders with larger bodies, such as tarantulas, we can still fully utilize the empty space for the body, but for slim spiders such as orb weavers, the space in the center is usually too large to be fully utilized.

To solve this problem, I looked into books on spider species, trying to find one with more features on the body so that I can fully justify the space in the center. And this particular spider soon caught my attention. It has a total of six spikes of its abdomen, a perfect choice for space utilization. The name "Micrathena" means "micro Athena", and "sagittata" means "arrow shaped".

In this design, I deliberately allocated the tips of each leg slightly off the edges of the sheet, making them strong enough to hold the body without installing steel wires. I also faithfully reflect the actual leg length differences in the design.

In retrospect, this design can still be improved quite a lot. The method I used to form the abdomen is overkill, and the last pair of spikes should be made longer (in some individuals, those spikes are really long). I also didn't make the color changing on the abdomen. I'm sure I would revise this design someday.

這篇文章 Micrathena sagittata, 2017 最早出現於 Tsai Origami。

This model was in some sense a tribute to John Montroll, who is the first person in origami history to accomplish the same subject from a single uncut square, with the correct number of major appendages, which was published in Animal Origami for the Enthusiast (1985). I try to use the smallest possible grid size to achieve all major features comparable to Montroll's design while making it 3D and optimally efficient. I managed to do all that in a grid size of just 25 (with some half-unit structures). I wouldn't say it's not possible to use an even smaller grid, but very likely the result would be off in proportion.

Anthropods are especially suitable subjects for uniaxial box pleating, hence there's no need to bring ERM into this design. Still, I present the map in the figure above with lakes to show where the body is allocated. One thing about uniaxial box pleating is that in many cases there would be no land at all.

The crease pattern of this design uses a variation of GOPS near the head, which was originally discovered by test folding. The studying of that particular pattern later leads to the discovery of the general transformation rules of GOPS.

這篇文章 American Lobster (Homarus americanus), 2016 最早出現於 Tsai Origami。