3D Printing with Flexible Filament

We’ve been experimenting with NinjaFlex filament here at Adafruit and we’re delighted to share with you our experience with it so far. We’ve had the opportunity to find three categories of things that work pretty well with 3d printed flexible material.

The Material

It’s very flexible. Almost silicone-like. It stretches, bends, twists and folds without deforming the printed objects original shape. Sturdy enough to hold it’s own shape and doesn’t flop over with a minimum wall thickness of 2mm. Similar to PLA, it handles 90 degree overhangs better then ABS. The filament prints well at 225c and works with most FDM printers. Printers with a plunger filament loader like the makerbot replicator will require a spring-loaded filament loader upgrade. Our makerbot replicator wouldn’t load the filament, so we had to upgrade ours. Flexible material sticks to acrylic build plates, blue painters tape and Kapton tape. Prints tend to have issues with the first layer adhering to the build so live leveling  ensures the first layer fuses. Removing flexible parts from the  build plate is easy and well, quiet pleasing. Most 3d printing operators know how fun it is to remove ABS and PLA prints. With Ninjaflex, It’s both fun and scary to remove because its so flexible and elastic. The first test prints we couldn’t help but feel like we were deforming the shape or going to tear it apart. No need to scratch up that build plate with a scrapper when your part is strong and flexible, just pull and peal!

The first tests are always a bit messy, objects with surface detail tend to accumulate stringy access material which sometimes can get burnt and discolor when too much hits the nozzle, so be sure to keep the nozzle clean. Objects with geometry that make the head move across multiple islands is going to have considerable artifacts that may require clean up. Removing these artifacts can be a bit of a stretch. Fine scissors work well, carefully tug on the access with tweezers and snip them off. Compared to ABS and PLA, ninjaflex is a little messier but overall a very practical material.

Stress Test

We wrapped an iPhone case prototype print around a 50 pound barbell weight and let it hang on a hook over nigh to test strength and reshaping properties. The bumper held up the weight but it stretched out to the point where it lost its original shape. Though it can handle quick tugs of excessive stretching.  Even using our bare hands, we couldn’t quite rip it apart. With enough thickness, it’s some really tuff stuff!


Watches, bracelets, necklaces, shoes, hats, head bands, and even purses (considered wearables?). That’s just a few of many applications we have yet to experimented with but we’re working on it! Our latest wearables using 3d printed flexible material is a classic application, a wrist band. Our design prints well with minimal clean up. Figuring out the tolerances for the snap pins required a handful of iterations but its a good example of testing the material for snapping properties. For housing the electronics, we avoided using hard plastic and made a cap that would hold the circuit together when held down on your wrist. There’s a lot to experiment with in this category.

LED Diffusers

Looking for a way to soften the super bright glow of a NeoPixel? Design and make your own diffusers with flexible filament! With a wall thickness of around 1-2mm, hollowed objects can make really nice light diffusion. We made round domes and spiky caps that nicely fit over our sewable NeoPixels. These worked great on our latest Chameleon Scarf 2.0 project and really illuminate the fabric. During the holiday break, we made a hallow snowman and a pumpkin to test how well the material handles geometry. Not only did the parts retrain surface detail and shape, they lit up quite nicely. We’re definitely working on incorporating this material in more wearable projects!

Device Cases

The first thing we tend to print is a case for our mobile phone. Being that it’s the thing we touch most of the day, it’s a great way to test material. We’ve designed our own iPhone cases and optimize our bumper for ABS and PLA material. That being said, we’ve come accustom to them wearing out (after a month or two) from the wear-n-tear of every day use. They can, and do break after a few occasional drops. Finally, we have found a way to make 3D printed iPhone cases indestructible. Flexible filament makes an awesome bumper because it doesn’t break. It actually protects our phone better and when dropped, the material absorbs the fall more efficiently when ABS or PLA. It also give the phone a bit more grip when placed on a table.

All this being said, we didn’t think twice when printing our iBumper model that was optimized for ABS. Just to find out the tolerances were completely off with this flexible stuff. We had to completely redesign our master model. The trick to making a flexible case work was to design from the inside of the iPhones dimensions. We leverage the elastic-stretchy properties of the material to make it grip onto the device tightly. We also added beveled buttons to the power and volume button controls. It’s worked out pretty damn well. Check out our design on thingiverse if you want to try it out yourself!

Thingiverse Community

Here’s a few great finds on thingiverse. These are examples of what NinjaFlex filament is great for! What awesome stuff would you make with flexible material, what stuff should we make? Let us know in the comments below!

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