[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.
Use the caulking gun style ‘syringe’ silicone comes in.
Perhaps just poking a hold in the stock plastic nozzle and re-zeroing for each tube.
Perhaps w a fixed metal nozzle the tube drops into.
Have to blead each tube first…cut the tip, break the film, pump until air is cleared.
Really want to get ambitious, one step to zero, cut, poke (perhaps optional) and blead.
CNC caulk tube mohel.
Weight is ‘only’ 10oz (FREEDOM!) for a full tube.
That’s about two NEMA-17s.
Going to be a fat print head to push the plunger down.
Rotating nut on a screw w an alignment notch?
Metal tube holder is front of caulking gun.
10 oz per reload not ‘feature’ other way either.
Anybody know what the useful % of this filament is?
More than 10oz of silicon delivered per spool pair?
It would kinda suck to need to buy a new mixing nozzle every time I do a print, simply everyone of them gets clogged with dried silicone after it’s done.
simply because every one of them*
These can usually be disassembled, and cured silicone wont stick to the plastic (HD/LD PE, presumably)
You can also reuse a condom by turning it inside out and shaking it vigorously.
Crack it like a whip, don’t worry about what’s downrange.
Pre-lubed.
Peristaltic pumps is what I was thinking. They were used on my IV when I was in the hospital. If it’s accurate enough for dosing chemotherapy, I would expect it could be used for a printer. Then again, maybe not. With IVs, you can increase the accuracy almost arbitrarily by increasing the dilution of the medication.
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.
“this looks like a way that is designed to extract as much money from the customer as possible”
Exactly. What a waste of resources.
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.
I’d suggest this has value because of how simple it is to integrate into your regular workflow, it is just loading up another spool – syringe either add lots of mass at the tool head and/or run out often and are messy to handle and refill.
So your prototype and more bespoke parts 3dprinting/engineering shop with their multi tool head machine already is going to find the procedure change to add this capability to what they do pretty trivial. If you are running machines in ‘high’ volume the just slot in another likely very very expensive filament probably still works out more profitable than wasting man hours filling and cleaning up the syringe even though the material and tool head would likely be significantly cheaper.
One of us random tinker probably doesn’t find it worth it, as the syringe type designs have been done (though maybe not to the quality Prusa likely did), are probably much cheaper and the consumable material certainly will be, so when we are not doing it all day every day and don’t tend to value our time into the costs of the more hobby tinkering…
The next closest solid nn printer I’ve seen on the market starts at around $13,000 so this doesn’t look like they’re ripping people off.
At least one that’s reliable and not some bodge of hardware where the only updates come every six months on GitHub.
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.
Does anyone see two separate extruder motors? I can’t tell if it’s set to use the optimal ratio of the only filament available or if you can tune it to use different mixing ratios.
Also, why is there still a brass nozzle and hotend on the toolhead? Maybe it’s a removable piece that attaches to an existing toolhead, or they’re just showing a working prototype or something.
It’s a cool idea, regardless.
It’ll be interesting to see if this is a more cost effective means than using a resin printer.
This looks like an incredibly expensive alternative to using tubes just to be able to treat it like other filaments when a Bowden type tube could be arranged with a similar mixing end just as adaptable, and likely for far less.