Ben's Merkaba Star — Spinner, Rocker, Roller, Spring, Chain — Toy/Decoration

prusaprinters

<p>This design started with just the merkaba star shape to fill a request from my father. It was fun to model, and turned out nicely with the clear Colorfabb XT filament. Then I discovered that it could be printed in spiral vase mode and I realized it was something special. I scaled it down to make it the more compact desk toy and decoration you see here. I found that it worked best to use a .6 mm nozzle with .3mm layer height for the star in vase more, which makes it much more durable and transparent than with the default nozzle and layer height. It ended up with it only taking 2.4g of material and 12 minutes to print! With it oriented as I have it, it's always moving on 45 degree angles, so it goes a bit faster. It's really fun and mesmerizing to watch. And you can print four of them sequentially on the MK3s in one go (maybe five, but I didn't want to push it). It should work fine with other filaments (especially PETG), but I haven't tested them. I'd love to see other makes!</p><p>I decided to make a holder for it which would allow the star to be rotated within. I love superellipse shapes, and saw that one would fit well here. I didn't use a mathematical equation to generate the curve, but it's a fairly good approximation. Starting with that, I made some indentations to hold the points of the star. I made them just a bit small so that the holder ring would flex and then hold the star firmly. I discovered that it has an interesting property where you can press on the sides to flex the ring very slightly and loosen the grip on the star to the point where it will rotate quite freely. Since the star is so light for its surface area, this means that if you blow on it just a bit to the side of its rotation axis, it will spin incredibly quickly while making a satisfying whirring sound. Just don't get too close or it might nick your lips!</p><p>With that part in place, I wanted to design a way to be able to prop it up on my desk. At first I made a simple circular platform with a groove to hold the ring, but that was boring and difficult to get to fit just right. So I returned to the superellipse motif and made a couple of clamping supports, and added indentations in the holder ring so they could lock into place. The fit on these is somewhat precise, so the standard .4 mm nozzle works best, and PETG gives it the required flexibility properties. The design of these was an interesting challenge, since they needed to be able to expand and clamp down in the right position, so I had to model and print them in the collapsed position. I worked out that they rotate around the lowermost point, so I was able to use a circular sketch pattern to align things properly. These supports have a shape that allows the whole assembly to rock back and forth for a while when you tilt it. They also allow it to be positioned in several different configurations.</p><p>While playing around with it, I realized that the supports could be linked together in a few different ways. One way is that they just intersect each other in a plane. That's kind of neat, and can be cooler when you add more (like the Olympic rings), but the really cool configuration is when they are linked together perpendicular to each other, making an X shape. Now they have the ability to roll along in an interesting manner, as well as to gain a springiness. If you press and release it just right you can make it jump over a foot! I took a bunch of photos to demonstrate these properties. It's a lot of fun.</p><p>Once I printed a whole bunch of them, I realized they could be linked together in a big chain to make decorations for lights. The stars look really beautiful when the light is shining through them. With a long enough chain, they'd even make a good garland for a Christmas tree or other holiday decorations.</p>