Make Custom Shirts With A 3D Print, Just Add Bleach

February 10, 2025 by Donald Papp 38 Comments

Bleach is a handy way to mark fabrics, and it turns out that combining bleach with a 3D-printed design is an awfully quick-working and effective way to stamp a design onto a shirt.

Plain PLA stamp with bleach gives a slightly distressed look to this design.

While conceptually simple, the details make the difference. Spraying bleach onto the stamp surface helps get even coverage, and having the stamp facing “up” and lowering the shirt onto the stamp helps prevent bleach from running where it shouldn’t. Prompt application of hot air with a heat gun (followed by neutralizing or flushing any remaining bleach by rinsing in plenty of cold water) helps keep the edges of the design clean and sharp.

We wondered if combining techniques with some of the tips on how to 3D print ink stamps would yield even better results. For instance, we notice the PLA stamp (used to make the design in the images here) produces sharp lines with a slightly “eroded” look overall. This is very much like the result of inking with a stamp printed in PLA. With a stamp printed in flex filament, inking gives much more even results, and we suspect the same might be true for bleach.

Of course, don’t forget that it’s possible to 3D print directly onto fabric if you want your designs to be a little more controlled (and possibly in multiple colors). Or, try silkscreening. Who knew there were so many options for putting designs onto shirts? If you try it out and learn anything, let us know by sending in a tip!

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The Lowest-Effort Way Yet To Make 3D Printed Lenses Clear

February 4, 2025 by Donald Papp 30 Comments

This technique shared by [Andy Kong] is for 3D printed lenses, but would probably be worth a shot for any resin prints that need to be made nice and clear. The link to his post on X is here, but we’ll summarize below.

It’s entirely possible to print lenses on a resin printer, but some amount of polishing is inevitable because an SLA print still has layer lines, however small. We have seen ways to minimize the work involved to get a usable lens, but when it comes right down to it the printing process creates tiny (but inevitable) surface imperfections that have to be dealt with, one way or another.

3D-printed lenses fresh (and wet) from the printer look clear, but have tiny surface imperfections that must be dealt with.

One technique involves applying a thin layer of liquid resin to the surface of the printed lens, then curing it. This isn’t a complete solution because getting an even distribution of resin over the surface can be a challenge. [Andy] has refined this technique to make it ridiculously simple, and here’s how it works.

After printing the lens, place a drop of liquid resin on the lens surface and stretch some cling wrap over the lens. The cling wrap conforms to the shape and curve of the lens while trapping a super thin layer of liquid resin between the cling wrap film and the lens surface. One then cures the resin while holding the cling film taut. After curing, [Andy] says the film peels right off, leaving an ultra-smooth surface behind. No tedious polishing required!

But what about the flat back of the lens? [Andy] suggests that instead of using cling film (which is better at conforming to a curved surface) simply use a drop of resin in a similar way to bond the flat side of the lens to a smooth piece of glass. Or bond the backs of two lenses together to make a duplex lens. This technique opens quite a few possibilities!

Even if one isn’t 3D printing optical lenses, we suspect this technique might be applicable to making crystal-clear 3D prints with a little less effort than would otherwise be needed.

Keep it in mind, and if you find success (or failure!) let us know on the tips line because we absolutely want to hear about it.

A guy's leg encased in a 3D printer showing a fresh printed tattoo

Do, Dare Or Don’t? Getting Inked By A 3D Printer

February 2, 2025 by Heidi Ulrich 19 Comments

This unusual tattoo hack by [Emily The Engineer] is not for the weak of heart, but let’s be frank: we kind of know her for that. And she gives out a warning, albeit at a good 10 minutes in, to not do this at home. What she’s about to do takes creativity and tech obsession to the next level: to transform a 3D printer into a functional tattoo machine. Therefore, [Emily] ingeniously modified one of her standard 3D printers to operate two-dimensionally, swapped its plastic extruder for a tattoo gun, and, yes, even managed to persuade a willing participant to try it out.

The entire process can be seen in [Emily]’s video below, which humorously yet meticulously documents the journey from Sharpie test runs to actually inking skin. Aside from a lot of tongue-in-cheek trial and error, this project requires a sheer amount of problem-solving. [Emily] employs firmware edits to bypass safety checks, and clever hardware adaptations to ensure smooth transitions between strokes. One impressive upgrade is the emergency solenoid system, a literal panic button to stop the machine mid-tattoo in case of trouble—a critical addition for something with needles involved!

This hack sits on the edge of DIY body modification, raising eyebrows and technical questions alike. If you missed the warning and are now frantically searching for tattoo removal options, know we’ve covered some (but you might be rightfully scared of automating that, too, at this point). If you haven’t lifted a finger while reading this, just do the safe thing: watch [Emily]’s video, and tinker about the subsequent purposes this discovery creates for 3D printing or tattoo art.

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Tiny RC Four-Wheeler Gets Chassis Upgrade For More Traction

February 2, 2025 by Lewin Day 9 Comments

[Azpaca] purchased a fun little toy car from Tamiya, only… there was a problem. The little off-roader wasn’t up to scratch—despite its four-wheel-drive, it couldn’t get over rough ground to save its life. Thus, it was time to 3D-print a better chassis that could actually get through it!

The problem was quite obvious. With no suspension and a rigid chassis, the vehicle would tend to end up with one or more wheels on the air on rough surfaces. To rectify this, [Azpaca] created a twisting chassis which would allow the wheels to better remain in contact with the ground. The design is relatively straightforward, and reuses much of the original drivetrain, including the simple brushed motor. However, with a pivot right behind the front wheels, it has much more traction on rocks and gravel, and can traverse these terrains much more easily.

Tamiya’s motorized toys aren’t particularly well known in the West, but it’s neat to see the community that exists around modifying them around the world. Design files are available for the curious. If you’re not down with mods, perhaps you’d prefer to print your own cars from scratch. Video after the break.

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Using Microwave Heating To Locally Anneal CNT-Coated FDM Prints

February 1, 2025 by Maya Posch 19 Comments

The CNT coating between the layers is heated with microwaves to locally anneal. (Credit: Sweeney et al., Science Adv., 2017)

Layer adhesion is one of the weak points with FDM 3D printing, with annealing often recommended as a post-processing step. An interestingly creative method for this was published in Science Advances back in 2017, featuring the work of researchers at Texas A&M University and citing previous work by other teams. In the paper by [Charles B. Sweeney] et al, they describe how they coated PLA filament with carbon nanotubes (CNTs), resulting in this CNT being distributed primarily between the individual layers of polymer.

This is useful because CNTs are quite sensitive to microwave radiation, resulting in the conversion to thermal energy, i.e. heat. Compared to traditional annealing where the entire part is placed into an oven or similar, this microwave-based heating – or locally induced RF (LIRF) as they call this method – localizes the heat to the interface between two layers.

The advantages of this approach are that it doesn’t change the dimensions of the part noticeably, it’s faster and more efficient, and the annealing between layers approaches the strength of traditional manufacturing. Unfortunately not too much seems to have happened with this approach since then, but considering that both CNTs (single & double-walled) and microwaves are readily available, there’s not much standing in the way of replicating these results.

Could Non-Planar Infill Improve The Strength Of Your 3D Prints?

February 1, 2025 by Lewin Day 24 Comments

When you’re spitting out G-Code for a 3D print, you can pick all kinds of infill settings. You can choose the pattern, and the percentage… but the vast majority of slicers all have one thing in common. They all print layer by layer, infill and all. What if there was another way?

There’s been a lot of chatter in the 3D printing world about the potential of non-planar prints. Following this theme, [TenTech] has developed a system for non-planar infill. This is where the infill design is modulated with sinusoidal waves in the Z axis, such that it forms a somewhat continuous bond between what would otherwise be totally seperate layers of the print. This is intended to create a part that is stronger in the Z direction—historically a weakness of layer-by-layer FDM parts.

Files are on Github for the curious, and currently, it only works with Prusaslicer. Ultimately, it’s interesting work, and we can’t wait to see where it goes next. What we really need is a comprehensive and scientific test regime on the tensile strength of parts printed using this technique. We’ve featured some other neat work in this space before, too. Video after the break.

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Time Vs Money, 3D Printer Style

February 1, 2025 by Elliot Williams 28 Comments

A few months ago, Hackaday’s own Al Williams convinced me to buy a couple of untested, returned-to-manufacturer 3D printers. Or rather, he convinced me to buy one, and the incredible success of the first printer spurred me on to the second. TL;DR: Lightning didn’t strike twice, but I’d still rate it as worth my time. This probably isn’t a good choice for your first printer, but if you’ve done the regular maintenance on your first printer already, I’d recommend it for your second or twelfth.

As background, Al has been volunteering with local schools to teach a 3D printing summer class, and this means outfitting them with a 3DP lab on the dirt cheap. His secret is to buy last year’s model which has all of the features he needs – most importantly for the kids, automatic bed height probing – but to buy it from the scratch-and-dent shelf at Creality. Why? Because they are mid-grade printers, relatively new, but on deep discount.

How deep? I found an essentially endless supply of printers that retail for $300 on discount for $90 each. The catch? It might work, it might not. I bought my son one, because I thought that it would at least make a good project for us to work on together. Those plans were spoiled – it worked absolutely flawlessly from the moment we bolted it together, and he runs 24-hour jobs on the thing without fear. From the look of the build plate, it had been used exactly once and returned for whatever reason. Maybe the owner just didn’t want a 3D printer?

The siren song of straightforward success was too much for me to resist, and I picked another up to replace my aging A8 which was basically a kit for a 3D printer, and not a particularly good one at that, but could be made to work. My scratch-and-dent Creality came with a defective bed-touch sensor, which manifest itself as a random absolute refusal to print.

I took it apart, but the flaw is in the design of the V1 touch sensors – the solenoid requires more current to push down than the 3DP motherboard can reliably deliver. It works 100% of the time on my bench power supply, but in situ it fails about 30% of the time, even after hitting it with graphite and making sure everything is mechanically sound. Creality knows this and offers a free trade-in, just not for me. The new version of the Creality probe costs $50 new, but you can get cheap knock-off BL Touch models for $14. Guess what I did?

And guess what bit me? The cheapo touch probe descends a bit slower than the Creality version should, and the firmware is coded to time-out in an extra-short timeframe. Thankfully, Creality’s modifications to Marlin are all open source, and I managed to tweak and flash a new firmware that made it work 100% of the time, but this was at a cost of probably eight hours of bug-hunting, part-ordering, and firmware-compiling. That said, I got some nice extra features along the way, which is the advantage of a printer running open-source firmware.

So my $300 printer cost me $105, plus eight hours of labor. I only charge one coffee per hour for fun hardware debugging tasks, but you may have a different valuation. Taken together with my son’s printer, we have $600 worth of printer for under $200 plus labor, though, which starts to sound a little better.

Is gambling on an untested return 3D printer worth it? For us, I would say it was, and I’d do it again in a few years. For now, though, we’ve got three printers running and that’s all we need. Have you gone down this perilous path?