The Base Architecture
No matter how simple or complex any of the butterflies from our system may be, they each display many of the distinguishing features of their living counterparts: head, thorax, abdomen, forewings, and hindwings.
You will soon be defining all of these exciting features, but we need to begin with the foundation of the basic architecture that Michael developed in 1978 with his Butterfly for Alice Gray (page 34). Find a piece of letter paper and fold along with us as shown in the next few diagrams.
1. (A) Valley-fold in half, long edge to long edge. Unfold. (B) Valley-fold short edge to short edge.
2. Squash-fold the right half. Look ahead at steps 3–5 to understand the process.
3. The squash fold in progress.
4. The squash fold almost complete. Press flat.
5. Your paper should look like this. Turn over, left to right.
6. Squash-fold the right half.
7. The squash fold in progress. Press flat.
8. Valley-fold the bottom corner to the top of the split. Unfold.
9. Squash-folding the right and left halves to form the wings.
10. The squash fold in progress. Press flat.
11. The “LaFosse Butterfly Base.”
1. Fold in half, bottom to top.
2. Squash-fold, and then flip and repeat on the reverse.
3. Valley-fold the bottom corner to the top of the split. Unfold. Squash-fold the left and right halves to form the wings.
4. Move the top layers of each hindwing upward. Mountain-fold the existing horizontal crease and add a valley fold below, forming a crimp in the middle of each wing.
5. Inside-reverse-fold the corners of each wing.
6. The “Dollar Bill Butterfly Base.” Complete the butterfly by following finishing steps for other projects described in the book.
Some rectangles, such as those used for most paper money, will produce bases with top-layers that extend beyond the normal wing margins of the base, and will usually provide no margin of paper for the head and thorax. However, you can make a head/thorax margin out of the upper 5th of the body paper, as shown in step 3, and you will need to form a crimp, as shown in steps 4 and 5, to differentiate the forewings and hindwings.
Customizing the Base for Variety
When preparing a base, place the first fold, or “horizon” crease, along the center by matching the lower edge to the upper edge (just fold the sheet in half). This is the butterfly’s “waistline,” separating forewings from hindwings. (A short portion will become the head and abdomen). Sharp creases are essential, so burnish every crease with the back of your thumbnail. (Or use a folding tool, a “bone folder,” or even the bowl of a spoon. Do not use anything that can bruise or mar the paper’s surface.) Placing the horizon crease above the center of the square will create smaller forewings and larger hindwings; placing it below will do the reverse. Open the paper. Keep the horizon crease horizontal.
There are many ways to form margins that result in a rectangle of suitable proportion. When measuring distances along the edge of the square, we like to make a short pinch as a reference mark at the edge (do not make a full length crease). Beginners may prefer to pinch a reference point along the other edge too, especially when folding a narrow margin flap accurately.
These diagrams show how to fold different proportions that contribute to the wide variety of origami butterfly bases from which to choose.
These early steps determine many possible outcomes. The photos show the initial set-up decisions (at left), and the resulting bases (at right) for some favorite butterfly models.
The photos to the left show some of the most common base variables.
In the top example you can see the effect of beveling the corners of the visible flap: triangular eyespots appear on the forewings.
Each setup will always provide you with two alternatives: fold in half to the front (for the result on the right) or fold in half to the back (for the result on the left). A different base results in each case.
There are numerous combinations and possibilities regarding the orientation and size of margin flaps and corners. The margin flaps can be folded to the front, to the back, or with one on each side. The most versatile initial setup approximates the ratio of the Golden Rectangle, and when you fold over a pair of 3/16 flaps, the resulting rectangle’s ratio of length to width will be within 2% of the Golden proportion! We routinely do this by first pinching marks at the 1/4, and at 1/8 positions, and then by aligning one pinch on top of the other, and creasing all the way across the square (along the midpoint between the two reference pinch marks), you will have defined a flap measuring 3/16 as wide as the square. Repeat with the opposite edge. Some designs require the corners of these margins to be folded—some to the outside, others tucked beneath.