7 mystifying 3D-printed optical illusions to make this weekend (Oct 2 - 4)

Credit: Tim Brookes / How-To Geek Published Oct 2, 2026, 12:01 PM EDT Tim has been covering technology for almost 20 years, in that time spanning a broad range of topics from security to product reviews. He is especially focused on the Apple ecosystem, productivity, and consumer advice. Over the years Tim has written thousands of articles, reviews, and round-ups in addition to producing video content and original photography. A graduate of journalism, he found his footing as a freelancer with a laptop and loves how he is able to work from practically anywhere. Now a Senior Editor for iPhone, Mac, and Smart Home at How-To Geek, Tim still loves to write. He can also be found crafting round-ups and productivity posts for the Zapier blog. Earlier in his career Tim spent nearly a decade as a writer and eventually Apple section editor for MakeUseOf. Tim currently lives in Brisbane, Australia. Outside of work he loves to hike and work out, play video games, and spend quality time with his wonderful partner and two cats Inka and Roger. Sign in to your How-To Geek account Some of my favorite 3D prints serve no practical purpose and yet are entirely captivating. Optical illusions fall firmly into this category, challenging your perception, inspiring wonder, and hopefully teaching you a few things in the process. Here are a few you might want to print this weekend. Penrose Triangle A real-life impossible shape The Penrose triangle was created in 1934 by Swedish artist Oscar Reutersvärd. It depicts a three-sided shape that overlaps in a manner that simply cannot exist in real life. That also means it can’t be 3D printed either, but you can print your own illusory Penrose triangle and attempt to experience the effect for yourself. In reality, it only works from one angle. Get the perspective just right, and you have your very own impossible shape. Infinite cube It looks great, whatever it is Credit: fifindr / MakerWorld The infinite cube might not technically be an illusion, but it’s still a fascinating model to look at. The cube exists as one solid piece, with no intersecting lines, giving the illusion that certain parts of the cube are floating and unsupported. This artistic design piece makes for an interesting little sculpture, and you can scale it up or down to suit. ”Impossible” uphill rolling cone A truly fascinating illusion Credit: fr33lab / MakerWorld You might remember this one from physics class, and it’s still just as fascinating to watch as it was all those years ago. This two-part model consists of an angled ramp and a double cone. Despite the angle of the ramp, the cone will always roll “uphill” since the center of mass is lowering thanks to the shape of the cone. Print your own impossible double cone and see for yourself. Jastrow arc optical illusion A mind-bending illusion Credit: Cipriani 3Design Studio / MakerWorld The Jastrow illusion—also known as the Ring-Segment illusion, Wundt Area illusion, and Boomerang Illusion—is a fascinating effect that causes you to perceive two identical arc shapes as being differently sized due to how they are placed. The arc at the top appears smaller than the one at the bottom, though they occupy the same area. You can test this for yourself by making your own Jastrow arc optical illusion. If you’d like to use a little less filament, you can print a simplified version that demonstrates the same effect. Ames room illusion Print your own scale model of a distorted room An Ames room is an illusion that you might have seen in a gallery or other interactive exhibit, where a seemingly rectangular room causes the sizes of the objects within the room to distort when moved from one side to the other. The illusion only works when you view the room from the intended perspective, but the effect is pronounced and fascinating. In reality, the room is shaped like an irregular hexahedron which you will see when you 3D print your own Ames room. The model only covers the room, you’ll need to provide your own objects in which to go in it (consider printing some of your own miniatures). Zoetrope illusions Spin for the win Credit: GepART / MakerWorld A zoetrope is a primitive means of displaying animation that rose to prominence as a child’s toy after it was introduced in 1866. It’s a spinning cylinder with gaps in its housing that displays cells in sequence to form a smooth animation when spun at the right speed. There are quite a few of these models to choose from that you can download and print yourself. The best Zoetrope on MakerWorld includes strips that you can swap in and out so that you can experience different animations (plus optional magnets). Alternatively, there are spinning tops that work in the exact same way: spin the top to see the animation. You can even generate your own if you want to customize the message within. Scanimations animated illusion Another fun animated illusion Credit: Hiro Koiso Racing / MakerWorld Dubbed scanimations, this sliding viewer turns static images into looping animations as you move the top screen. It includes five different animations, all of which are printed directly onto filament. You could also try generating your own scanimations with a generator to print and use instead. For a slightly more practical implementation of this effect, take a look at the DuoShift optical illusion sign. Looking for more things to make this weekend? Check out last week’s collection of modular 3D printing projects.