5 useful 3D prints that can help you make better online shopping decisions

Published Sep 27, 2026, 12:30 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. Buying things online is the best way to save money, but it can be hard to know if you’re buying the right size or measuring properly. Getting this wrong means dealing with returns, which is inconvenient and best avoided. Luckily, these 3D prints can help boost your chances of success the first time around. Buy shoes online with confidence Credit: thiz3D / MakerWorld If you’re reading this, you probably know your own shoe size. Despite this, different shoe manufacturers use different sizing and fit guides and often resort to measurements like millimeters to help you make the right choice. At the same time, buying for children can be hard since their feet are growing (and not always at a consistent rate). That’s where the HappyFit foot gauge comes in. This model is available in a variety of styles, including V4 with an EU and US scale and the latest V5 with millimeters and standard EU sizing. The model prints in two pieces, and requires a printer with a 256cm x 256cm build plate. The measuring slider includes a half-size buffer so you can balance a perfect fit with comfort. Tip: Millimeters are seen as the most accurate measure when gauging shoe size online since different manufacturers size their shoes differently. To buy with confidence, look for a sizing guide that displays the size of the shoe in millimeters and use that. Ring and smart ring sizing kits Say “I do!” to more jewelry If you’re shopping for jewelry, you might want to try it on before you part with the cash. But this is not always the case, nor is it always necessary if you know your size. In this case, printing your own ring sizing kit at home can be really helpful. Do this using a universal ring sizer (this one is based on US sizes; other regions may vary). If you’d rather feel what the size is like on your finger, you can print individual sizing rings instead. Smart rings are a little different, since they are produced in a much smaller range of sizes. You can download Oura sizing guides or Amazfit sizing guides (among others) to help you decide. Watch and smartwatch sizing guide Watch and see Credit: ropesgames / Printables Like jewelry, a watch can be a very personal item. You can spot a model that you like the look of online, but without knowing how it fits on your wrist, it can be hard to gauge whether it’s right for you. This is especially true if you have smaller wrists, where large watch faces can easily dominate. A good option if you can’t try the watch on in person is to print a parametric watch case sizing guide. Since the model is parametric, it can be resized in FreeCAD and exported so that you can print something that fits accordingly. You can also do the same with this bumper pack of smartwatch sizing guides. Apple, Samsung, Google, and others are constantly updating their models, so if there’s a particular watch case that you want to try, make sure you hunt for it on a model repository first. Print-at-home vernier caliper For measuring items and gaps accurately Credit: 3D Print Masters Hub / MakerWorld I bought a digital caliper right after getting my 3D printer, and it’s come in handy for a wide range of uses. I could probably have saved a few bucks if I’d printed a standard “analog” caliper instead. These were used for hundreds of years to design objects around accurate measurements. You can print your own caliper for next to nothing in two lengths, with an optional depth gauge add-on for measuring holes and other recesses. Pupillary distance measurer For buying glasses online Credit: LakerLab / MakerWorld I’ve worn glasses for as long as I can remember, and I make a fairly regular habit of getting my eyes tested and buying new glasses. I’ll pick my glasses in person, get properly fitted for them, and wait till they show up. This is great, but it’s also quite an expensive route. You can save a lot of money by buying glasses online, from companies that don’t have retail locations and therefore have lower operating costs. Though it’s important to make sure that your eye prescription hasn’t changed, I find these companies particularly compelling when it comes to buying cheaper glasses to wear without worrying about ruining your “good” pair. For this, you’ll need to know your pupillary distance when ordering your glasses. Thankfully, you can print out a pupillary distance ruler and take your own measurement—it certainly beats using the janky online webcam tools. Looking for more clever 3D prints? Check out these tags that can help prevent your stuff from being stolen.