Seahorse Square Tail

Fri, 30 Oct 2026 00:00:00 +0000

Background/Motivation

When I saw the MakerWorld Biomimicry Design Contest, the seahorse tail came to mind right away. A seahorse tail isn’t round, it’s square, made of small bony plates. Researchers found (Porter et al., Science, 2015) that the square shape grips better and doesn’t twist as easily as a round one. I wanted a model where you can actually see that tail curl.

At first the idea was a clamp, a seahorse that grabs things with its tail. Along the way it turned into a model that shows how the tail curls, and honestly that is the better version of it.

Model Design/Modeling

The tail is 14 square plates, print-in-place, getting smaller toward the tip like the real one. The joints only bend toward the belly, so the tail only curls one way. One cord runs along the belly like the muscle, and the black eye is the winding knob: turn it and the tail rolls up. The fin above the eye works as the release.

The joints were the easy part

I was most worried about 14 print-in-place joints in a row. I printed a few clearance coupons first, and a 0.2 mm gap in the design turned out right on my printer. The first full tail came off the bed with all joints free, and they hold well even if you try to pull a joint out sideways. That part just worked.

The ratchet that never locked

The first eye knob turned, but the teeth and the pawl never locked, in either direction. When I checked the print, the small sharp teeth came out rounded, so the real overlap between tooth and pawl was much smaller than in the design. On top of that the knob sat on a split post that wobbled. Basically, there was nothing left to hold.

The fix was bigger, solid hooked teeth, a matched pawl, and the knob printed in place in two bearings instead of a wobbly post. That one worked well on the next print.

If you ask me what I like most about this one, it’s the print in place again, especially the knob. The whole knob is printed in place, so it comes off the bed and you can just turn it, without any assembly. Yeah, that’s the part I like.

Small things you only find with your hands

The second print worked, but using it showed a few more things:

the fin was in the way when turning the eye with a thumb and finger, so the grip on the knob moved up above the fin
the holes in the tail were tight for the 0.6 mm nylon cord, so they became tall slots
the cord channel at the tail tip had a sharp turn, now it’s a smooth curve, and the exit under the eye gets bigger toward the end so the cord never meets a smaller hole
the knob had a bit of play, so it got more teeth and a tighter bearing

One more came from the slicer preview: the wall on top of the head was too thin over the release lever pocket. That got thicker before the final print.

Printing Notes

It prints in one piece, no supports, a bit under 4 hours, in white and black PLA Basic on my H2C with 0.2 mm layers. The joints and the eye knob come off the bed free, nothing to break loose.

Model Usage/Resources

Wind the eye and it clicks, the tail curls and stays curled. To let it go, turn the eye a tiny bit more, push the eyebrow fin, and let it unwind slowly.

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It’s a model to show how the tail curls, not a strong clamp. The files, the cord stoppers and the threading steps are on MakerWorld.

Hope you find it useful, and if you know an easier way to thread the cord, please leave a comment below.

Ball Launcher 2000

Thu, 22 Jan 2026 00:00:00 +0000

Background/Motivation

We have a ball-pit with a lot of balls. Kids of course liked it. Just one day, thinking about anything else we can do about it—kids also like to throw the balls around—then I was thinking, why not make a ball launcher that adds more fun to it?

Hence, the Ball Launcher 3000—it’s mainly for the kids to play.

Model Design/Modeling

This is part of my learning process in 3D printing and CAD modeling. This is a challenge in terms of the complexity of the CAD modeling, which includes many mechanical moving parts.

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Launching Mechanism

It consists of three moving parts: the button and two levers. Why this launching mechanism? It was inspired by one of my kids’ toys. There are of course many ways to “launch” balls—I guess it’s just a matter of choice.

Another important launch part is the barrel, which can rotate to set the launch angle. Last but not least, there should be a spring mounted under the launch button. For this, I simply printed a torsion spring and used hot water to “reshape” it. It’s not an elegant way, but it works.

The idea is that by pressing the button, it triggers a “chain-reaction” to the last lever, where the ball is, and it will launch the ball.

By the way, the ball is 50mm in diameter.

Color

My kids picked the colors—yes, I think it’s strange, but they seem to like it. Plus, it’s a good way to test my H2C multicolor printing.

Appearance

I just built around the launching mechanism with a box-like appearance. I know it’s boxy and boring, not really eye-catching, but again, they seem to like it.

Joining Two Parts

As you can see from the design, it consists of two halves. How to hold two parts together is a challenge for me. Of course, there are many ways to do so. For this model, I constrained myself to use a snap-fit approach.

After some YouTube learning and iteration, here is my design:

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Initially, the snap-fit parts didn’t have the extrude feature on the side, so the two parts could wobble side-by-side or up-and-down. By adding the side extruded feature with a tight clearance of 0.1mm, it makes the two parts hold up nicely and tight.

Printing Notes

This is not an optimized way to arrange different parts with different colors together, but I just want to test out the capability of the H2C multicolor print. Also, this is an over 24-hour print—again, just to check out the H2C’s performance with such a long print.

Model Usage/Resources

Launch balls for fun.

Assemble

This should be fairly easy. First, put all the snap-fit pins into the holes.

Then put all the parts in the slot.

Finally, put the other half of the case together.

By the way, you can see the torsion spring is ugly because, as mentioned above, I used hot water to reshape it. Anyway, it works and it’s inside the case—no one can see it. And my kids care even less as long as it works.

Notes/Lessons Learnt

There are several things that need to be improved:

The loading hole on the side is too big; need to somehow confine the ball.
It’s tricky to align two lever pins together when closing the case. Two solutions, maybe?
- Cut holes on the side such that the lever pins are accessible by hand when closing the case.
- Make the mount slots bigger such that the pins can align easily.

Toys on Plicatim

Seahorse Square Tail

Background/Motivation

Model Design/Modeling

The joints were the easy part

The ratchet that never locked

Small things you only find with your hands

Printing Notes

Model Usage/Resources

Ball Launcher 2000

Background/Motivation

Model Design/Modeling

Launching Mechanism

Color

Appearance

Joining Two Parts

Printing Notes

Model Usage/Resources

Assemble

Notes/Lessons Learnt