Origami Remora v2

Finish the tail area with 11.25

Remora use their suction-cup-like dorsal fin to hitchhike on larger sea creatures like rays, sharks, and whales.

Design

The 1st version haunted me in my dream. It's begging for a long overdue upgrade.

Let's begin by listing the issues:

1. The suction cup fins need proper pleated structure instead of mushed, with seam across the pleats.
2. Lower jaw need to jut out more prominently.
3. Eyes should not be a mush.
4. Tail fin should be triangular and slightly forked, instead of spade-like.
5. All other fins should be wider.
6. Most importantly, when seen from the side, the model shouldn't look as flat as roadkill.

Basically everything requires fix. Time to put everything I have learned in the past 6 years to redesign it.

The upgrade begin by allocating the pleats for suction cup fins that run diagonally. This pleat will also be used for the fins in the rear part, which shall be simply called "top" and "bottom" fin. The base would look like this:

A straightforward structure is to use bird base with border graft, that is further grafted diagonally.

The fat flap marked with orange rectangle will be distributed to make numerous smaller pleats like Kamiya's winged kirin. The other fat flap marked with light blue will be used as level shifter, bringing the suction cup fins protruding out of the symmetry line from inside. The suction cup fins will have color change, but I don't plan on making a color changed model.

The structure is promising. I tested with 30 cm paper to get better sense of how to make the face and tail area. Having used the pleat distribution technique numerous times, I'm confident about the suction cup pleats. It should be straightforward, so it was only folded up to 2 pleats during the test.

This test fold gave clearer idea. The fins near the head area are placed nicely behind the head, and can be spread like 'X' to match the actual fish. The excess paper in the front area can be boxpleated. The edges can be made into eyes that are accidentally color changed, and the long corner should be usable to make upper/lower jaw.

The suction cup was made to have seam that would cross all the pleats by simply folding the edges toward the symmetry line. This is kind of wasteful as many parts are buried inside. However, it eased the folding process. So I decided to keep it.

Making the pleated suction fins on the hypothetical base.

Left: the cross section of the suction fins, with plenty of wasted paper inside.
Right: the supposedly better layout.

One problem is the fins in the rear part. I could lift up the pleats, but the angle is too acute to qualify as remora's fin. 

Skinny pleat for the top fin.

Ideally it should appear from the middle, running all the way to the tail. This can be done with level shifting, but the body will have to be pleated, ruining the seamless body and shortening it.

Boxpleated level shifter that shorten the body.

I observed the cross section of the body and noticed there are plenty of accumulated paper inside. There must be a way to pull it out, and indeed, we can lift up the paper internally without using the standard boxpleated level shifter. This asymmetric structure produces top fin as envisioned. I also found an unorthodox way to create the tail. Looks quite nice and efficient.

Level shifting without shortening the body.

Okay, then what about bottom fin? I tried to use wilder asymmetric structure to bring the paper down. Looks good from one side, but not the other.

The bottom folded figure shows the "ugly" side.

I took a bit of detour to rework the upper fin. To make it seamless and easier to fold, it is simplified:

Seamless top fin.

There are still paper buried inside the body, so there must be way to pull it downward in the same fashion as the top fin. By playing on the test fold and using the "mush legalization" technique, I found a way to bring the paper down. 

Bottom fin pulled out.

Notice that this broke the level shifter, so the rear part of the suction fins trail farther than it should. This is solved by sinking & reintroducing the 22.5 version of the initial level shifter. Again, this is found by playing on the physical paper and using mush legalization. The tail is also upgraded to have forked structure with some 11.25. Finally the rear part matched what was envisioned.

Next the head. The eyes were pretty much final, but I still need nice way to make the mouth. It took numerous iterations on the test fold until the paper frayed. The problem was, the lower jaw is not only longer, it should also be wide and its width seamlessly integrate to the head. I couldn't find a good solution and resorted to a stylized pointy 22.5 flap. The model was not supposed to be realistic anyway (copium).

Finally on the last part, the pleated suction fins. The small flap of the bird base is split into 8, then slid in a staggered fashion. I quickly ran out of pleat to cover the entire suction fins, which is easily fixed by introducing a unit gap between pleats. However there is more pressing problem. Applying the classic technique requires sink on the bird base part, halving the width of the head. It became too skinny.

Left: unpleated.
Right: with pleats.
The part pointed by green arrow shows skinny head part.

The classic method I used all this time was derived from Kamiya's divine boar, and is used in his other model like winged kirin and fiddler crab. There is another one used by his horse. Instead of sink, it requires a valley crease running across the pleats.

Top: classic solution with sink.
Bottom: variant with valley fold instead of sink.

On paper, this looks like the bird base part and the pleated part remain closed with valley fold. Sadly this doesn't work in my case, because the crease dividing the bird base part and the pleated part is mountain fold. Confirmed in paper, there will be self-intersection.

I couldn't find way without sinking, but we can compromise. We know that sink will be used to produce squash-like structure. As long as the sink reaches the same height as the farthest pleat, there will be solution. The bigger the sink, the less space needed for the squash-like structure, which is what I optimized for in lamprey. So what if we optimize the other way around: make the sink as small as possible as long as the squash-like structure is within the allocated space?

Variant with minimized sink.
Top folded figure: optimized for maximized width.
Bottom folded figure: the classic with half width.

The produced transition unit resembles tightly crammed squashes. I was surprised how different the result looked like. It can be incorporated straight to the model. Using skinny sink here will result in more horizontal space consumed, but it is completely fine as such part is hidden underneath. It folds fine in Oriedita and I went straight to test fold.

The last test fold.

The small reduction in head width is acceptable. Also the pleat direction of the suction fins need to be reversed, so when the model is seen from the front, the shadow casted by the paper thickness makes the pleats look more prominent. Those are applied to the crease pattern below.

Fold

My test folds used 30 cm paper, around 50 gsm. The pleats got tiny but are still manageable. So I can use any paper around that size whose thickness is slightly more than double tissue. I used a 30 cm handmade paper made by Ansel out of raw cotton, which he gave me back in EBOC 2026. 

Folding the pleat distribution is tricky. First split the flap into 2. Then each halves are split into 1 : 3 ratio, and finally redistribute the 3 part into ones.

Precrease the pleats.

Initial collapse.

Release the trapped layers.

Rearrange to better lock the pleats.

Remarks

Having satisfied with how this model turned out, I am finally freed from the old remora haunting my dream.

Couple days after the final fold was posted, the copium wore out and I realized the lower jaw doesn't look right. It needs to be wider, or else the lower jaw looks like a tongue poking out. So it is fixed, but I didn't retake the picture.

Fixed lower jaw.