[Prusa] have a number of announcements, and one of the more unusual ones is that liquid printing is coming to the Prusa XL. Specifically, printing in real, heat-resistant silicone (not a silicone-like plastic) is made possible thanks to special filament and a special toolhead. It’s the result of a partnership with Filament2, and the same process could even be used to print with other liquids, including chocolate.
The process is as unusual as it is clever. The silicone is a two-part formula, but there is no reservoir or pump involved. Instead, there are two filaments, A and B. When mixed, they cure into solid silicone.
What is unusual is that these filaments have a liquid core. Upon entering the extruder, the outer sheath is cut away, and the inner liquid feeds into a mini mixing nozzle. The nozzle deposits the mixed silicone onto the print, where it cures. It isn’t clear from the demo where the stripped outer casing goes, but we assume it must get discarded or is possibly stowed temporarily until it can be removed.
Liquid-core filament is something we certainly didn’t have on our bingo card, but we can see how it makes sense. A filament format means the material can be handled, fed, and deposited precisely, benefiting from all of the usual things a filament-based printer is good at doing.
What’s also interesting is that the liquid toolhead can co-exist with other toolheads on the XL; in fact, they make a point of being able to extrude silicone as well as the usual thermoplastics into the same print. That’s certainly a trick no one else has been able to pull off.
There are a few other announcements as well, including a larger version of their Core One printer and an open-source smart spool standard called OpenPrintTag, a reusable and reprogrammable NFC insert for filament spools that gives you all of the convenience of automating color and material reading without the subtle (or overt) vendor lock-in that comes with it.
Watch a demo of the new silicone extruder in the video, embedded just under the page break. The new toolhead will be 1,009 USD when it launches in early 2026.
Neat idea, metering the two-part silicone by treating it like a filament. It remains to be seen whether this is better/easier/cleaner than a syringe/plunger based system, or even just a pair of small pumps drawing from a couple of bottles.
With that mixing nozzle, it’s a lot like those super-fast-set epoxies dispensed from a dual syringe with the replaceable mixing nozzle. That piece is certainly a per-session consumable. And you’re not going to be able to loiter around not pushing goo for a while: it’s going to set up in the nozzle.
It looks like the waste snakeskin is removed through that third fat tube. I wonder how often it gets clogged up with residual A & B components setting inside it. Betcha it’s a consumable too.
Looks like an off the shelf mixing nozzle; they’re like 2$ each or so.
The other benifit with silicone is it… doesn’t stick to things. I’ve literally been able to re-use mixing nozzles by pushing the core out and peeling off the cured silicone. Usually not worth the time for a 2$ nozzle, but it’s a lot more friendly to reusable hardware than epoxy.
I do wonder how a pair of peristaltic pumps fron 2 bottles would perform; I don’t recall what the volumetric accuracy on those is. Keeps the resin contact to just the tubes, replace them if they get clogged. I wonder what the cost of the filament vs standard silicone resin is.
Syringe dispensers would be nice, because keeping air exposure of the chemicals minimal prolongs their shelf life.
Maybe the nozzle could be a non-stick coating two-part design, that you open in half and take out the cured blob.
Now it makes me wonder how small you can make a progressive-cavity pump.
They are not very clear about how this works, but @ 02:30 you can (barely) see that the split open parts of the filaments are going upwards. Going back, @00:02 you can see the cut open pieces are fed into a third plastic tube.
But overall this looks like a way that is designed to extract as much money from the customer as possible, I have not looked up the cost of this filament, but I guess it’s on par with the USD 1000 printing head.
And if you’re going to do a new printer head, then why not simply use syringes? Printers that use syringes have been used for things like solder paste and clay to chocolate and other cake decoration materials.
True, the epoxy tubes with a mixer attached are just a few euros more than a simple mixer. It would not be a stretch to imagine something similar filled with silicone A + B.
But the pain is in dosing the correct amount and stopping when you need to. Filament printers are pretty good at that, but once you include pressure and flexible plastics you will have troubles with stringing.
Id rather stick with single syringe fed single component UV Cure silicone like Incure’s Pyra-Sil or Momentives INVISISIL and avoid all the complications of proprietary filled filaments and messy wasteful mixing systems.