Selective solar sintering with sand

[Markus Kayser] built an amazing solar powered SLS printer, but instead of using lasers and powdered plastics his machine uses the power of the sun to heat sand into complex shapes.

[Markus]‘ printer uses the same concept as his earlier solar cutter – burning things with a magnifying glass. Interestingly, the printer isn’t controlled with stepper motors and reprap electronics – it’s completely cam driven. The solar panels only power the motor attached to the frame moving on bearings made from skateboard wheels.

We’d guess that [Markus] is using a little more than 2 square meters of Fresnel lenses in his project. Since solar irradiance is about 120 W/m² (PDF warning), [Markus] is concentrating a lot of energy onto a point the size of a quarter, which would be necessary to heat up sand to its 1500° C melting point. The resolution isn’t what you could get with a laser, but [Markus] was able to print an amazing bowl along with other complex 3d shapes.

Check out [Markus]‘ video of the solar sinter printer after the break. There’s also a video of his previous experiment with the solar cutter.


  1. moldboy says:

    that is so cool!

  2. David Peters says:

    Hello Brian,

    The solar irradiance is about 1000 W/m², you missunederstood the PDF. Every irradiance that exceeds 120W / m² is considered “sunshine”, but most of the time, with lack of clouds you have 1000 W/m², even more on midday (around 1200 W/m²)

  3. eljonco says:

    If my 4.5 sqm of solar panels (50°N) can generate 500W at 15% cell efficiency, it is more likely that one square meter receives 1 kWh at noon. That makes the setup even more impressive… Ouch.

  4. buzzkill says:

    coolest thing ever on HAD. I wonder what the strength of the material is after fusing. Could you make blocks that could be cemented together to make larger constructions?

  5. theodore says:

    wow want

  6. Adam Outler says:

    That’s wonderful! What do you have in the middle of the desert? Sand, and Sun… This guy has basically created something out of nothing.

  7. Jonny says:

    Solar irradiation is more like 1200 W/m^2, not 120W/m^2

  8. Drake says:


    Minecraft? err solarcraft?

    Never thought about using sun to fuse sand … wants me to dig out my big Fresnel lens

  9. Till says:

    Next task would be upscaling and building a house. I would order a crystal summer house with a pool in the desert right now.

  10. spiderwebby says:

    if you could scale this up and automate it a bit more you could print houses… for free!!! (-ish)

  11. YO9GJX says:

    Fuse sand, just great.

  12. Abbott says:

    Actually, it is all driven by stepper motors and electronics… The solar cells provide the energy to run them.

    Sweet build though. I would love to play with one.

  13. Hackerspacer says:

    It’s like clockwork. People see a 3d printer and think – OMHAHZHAHGZZZ it can make ANYTHING!! TEA EARL GREY, HOT!!!

    Let’s be realistic for a moment. This is a neat project. It can fuse sand into a sort of glassy like material. That is very brittle, quite rough and possibly sharp and likely porous (I doubt that bowl holds water).

    Could you build a “house” out of it? Well, not right now – not with this build. But if you had complete servo powered control? Technically it would be a “house” in the sense that an igloo is a house.

    Most people wouldn’t want to live in a house made of fused silica sand but perhaps this idea has some merit given the amazingly low cost of sand.

    A properly engineered and built device of course would not be terribly cheap to build. I wonder how thick a wall you would need to create in order to properly support a “roof” of this material?

    Glass is HEAVY. Glass is brittle. Roofs don’t like to be supported by brittle things. But maybe this will give you a floor and 4 walls for “dirt cheap” pricing?

    • James Tipton says:

      Actually, glass has tremendous compressive strength. Like, most of the material the pyramids are made of contain lots of quartz. The problem is the air is reacting with the sand and creating tiny bubbles. That or he isnt melting the sand fully. It apppears like the particles melted together but didnt fully fuse. If it made glass,it would take time to anneal it. It cant go from 3000 degrees to room temp quickly or unevenly. If it does cracks develop.

  14. Hackerspacer says:

    A better design for dwelling building machine would be more of a GPS / micro accelerometer controlled device that can move about, take in sand, filter it and then deposit “beads” of fusable sand where needed, in order to build up a “floor” and 4 walls. Again, the “roof” would probably need to be built of other materials (or reinforced with steel – potentially embedded in or around silica sand?)

    The idea has potential but would need to be very well engineered. Done correctly though, such a system could very well create large “houses” for very, very little cost per unit.

    This build right now is really more of a crude, slightly manually controlled SLA system with a defined build envelope and decent resolution.

    It somewhat proves the concept though.

  15. Fogger says:

    Automate the whole process, and send them to the moon. Imagine what might be possible with no atmosphere and 2 weeks of continuous sunshine every month.

  16. Cpt. Obvious says:

    A bit on the slow side: add a second sun and you have a deal.

  17. DrNick says:

    This is what I once dreamed of! Thank you HAD for showing us. Spatial missions seem to be the best use for this due to its ability to build structures out of nothing. Also I’d like to build myself an igloo out of fused silica :)

  18. Miroslav says:

    Solar irradiation is actually up to 1000 W/m2.

  19. Hackerspacer says:

    Your comment about the moon and construction reminds me a bit of NASA’s EBF3 fabrication research.

  20. andar_b says:

    Interestingly enough…wouldn’t the amount of solar radiation reaching the moon (for example) FAR exceed what reaches the surface of the earth, per square unit? I’m guessing since the moon has no atmosphere to speak of.

    I wonder what could be done with a clay-type soil, would it be possible to fire the clay into a ceramic in layers?

  21. John says:

    Frickin’ artists… ;) I love it. Awesome production of the concept presentation.
    With refinement this will go a long way. From finer placement of material to spectrometry to place types of material, we might have a machine building “smart bricks” with circuits inside that collect their own solar power- without anyone on-site to supervise. nice.

  22. tinkermonkey says:

    I N T E R E S T L Y the Printer is driven by timing belts using either stepper motors or servos!! Much like reprap electronics. Only the cutter is completely cam driven. Look at the video! please keep the facts straight. I read your write-ups to decide which articles to further explore.

  23. anti-fanboi says:

    Neat. An art installation that produces art… If only he could have automated the addition of the “nothing” I mean sand.

  24. Wow, that’s pretty damned amazing to see.

    I would have thought it required a much larger concentrating lens to focus enough sunlight for those temps on Earth. I remember something about NASA wanting to have solar foundries on the moon to make lunar glass, and I assumed from that that it was only practical due to the lack of atmosphere or something.

    Admittedly I never gave it more than a passing thought.

  25. zuul says:

    pretty cool, and it’s sand,.. that’s like free most of the time

  26. Techartisan says:

    while drastically complicating matters….
    I would love to see a multiaxis attachment to hold a “workpiece” added to this….

    so that after he rough sinters a bowl…or even a sphere… the resulting part could be fixtured and “surfaced” with another pass.

    Additionally, It would be great to see parts where the native sand was “doped” with traditional additives that improve the qualities of various glasses.

    OVERALL, this was/is a GREAT project…

  27. William Betz says:

    Now if only it could create another Fresnel lens…
    It could be simplified to make bricks. Or maybe tiles. Imagine that it is focused on the ground and makes a tile. Then it roles forward and makes another tile. Automatically rolling across the desert and fusing sand as it goes. Sealing down the sand, trapping any moisture that gets into it.
    Perhaps we could push back the deserts.

  28. Alex Parting says:

    hack of the year?

  29. Greycode says:

    I think that living in a house made of this stuff would be hazardous to your health. It looks like there are edges capable of cutting human flesh, and it does not look as though it is thoroughly fused, which means you may also have a problem with silica dust.

    This however is a very cool project. Nice job.

  30. Bob Shaw says:

    The great value of this sort of solar sintering on the moon would be to mitigate the effects of dust on the various elements of a moonbase. Lunar dust is horribly abrasive stuff, and probably rather bad for you, but you could use a simple robot armed with reflectors/fresnel lenses etc to create an artificial ‘caliche’ surface which would reduce dust exposure considerably. Previous discussions on this subject suggested the use of microwaves for sintering the top layer of the regolith, but you could easily imagine a cheap, simple robot (perhaps following a string!) to do the job.

  31. jwstolk says:

    Very neatly done. It reminds me of solid objects created by lightning striking on sandy soil.

    I was surprised that fireproof socks do exist, but I still fail to see the advantage over fireproof gloves in this case :-)

  32. Techartisan says:

    I just want to throw it out that….this project didnt say anything about making buildings…

    “Solar-sintering aims to raise questions about the future of manufacturing and triggers dreams of the full utilisation of the production potential of the world’s most efficient energy resource – the sun. Whilst not providing definitive answers, this experiment aims to provide a point of departure for fresh thinking.”

    I think this discussion thread shows it succeeded….lots of thinking going on…

    Im already seeing jansenesque herds slowly wandering the desert leaving a trail of “interlocking fusion stones”…..

    Obviously if you were hoping to make “building blocks” slower plotting and thinner layers would increase “sinter fusion density”.

    and as for the fears of sharp edges or silica dust…..even if you fail to reach a smooth and beautiful finish….unless you were intending to use the resulting structure as nothing more then shelter…Id assume youd be doing some buildout? I mean nothing says your sandcastle cant be painted right? Id be perfectly content to trust a nice polyurea coating to lock the blocks in place and smooth it all out….

  33. Elias says:

    @Techartisan Wow that is some impressive stuff!

  34. MrX says:

    This is what hacking is all about. Seriously, the hack might not be very useful right now but I bet that with some polishing these guys can create master pieces.

    This is certainly one of the most creative stuff I’ve seen around here. I don’t say this too often: Props++ to the creators of the project!!

  35. Royboy says:

    WOW. One of the best things I’ve seen on Hackaday.

  36. Effigy says:


    you are right, if you built a house out of this, it would leak and likely not be strong.

    However, if you built a framework/basic structure out of this and composite/stucco over the outside, you’d be looking a lot better for sleepin’ through the night eh?

    regardless of the brittleness, it could be used ALA foam core to create a VERY strong composite structure without hauling in much material at all to a desert site. Maybe not ideal for everyone’s dream home but there are some refugees and soldiers around the world that just may be helped…

  37. Mark says:

    hack of the year – def

  38. eljonco says:

    Does ‘Gaudí cathedral’ ring a bell, folks? Think out of the box, be original. Cast the iron reinformcement bars far from you, use the strength of the structure itself. Yesterday I made icing on a cake, crumpled and cracked it seemed a complete failure, but with a little extra heat, the icing became smooth.
    You can do that with sand too.
    Sand dunes walk. So layer after layer you can just deposit your dwelling. Once it is finished, brush off the excess and glaze the outside.
    Change your ways and the future is bright. That’s what hacking is about.

  39. Deg says:

    You know, solar radiation approaches 1000W/m^2.. ah jk.

    This is so cool! Except it can’t anneal the glass properly, so any object will eventually explode (or just fall apart due to the sketchy sintered connections). Any time you melt glass you need to anneal it, which just means slowly lowering the temperature during a certain range. It melts/fuses around 1500F, and annealing range is maybe 750F to 900F, where temperature is dropped over a couple hours.

  40. TheCreator says:

    maybe he can sinter himself a more permanant office.

  41. hboy007 says:


    what would be possible on the moon? I guess yanking some chemically bound water out of the soil :-)

  42. Mythgarr says:

    @Hackerspacer – It should be noted that while glass is incredibly brittle, it also has an incredibly high compressive strength. Glass walls supporting a glass roof are doable – the issue would be crosswinds, debris, etc. Also, “People in glass houses” and all.

    I don’t think there are any sort of technical challenges to building a glass house, but the real-life concerns are considerable. What would you use for mounting doors, windows, pictures, etc? You can’t just drill out the glass or nail something in like you could with stick built or metal stud framing.

    I am interested to know what the “point” is. If he’s trying to make a very green 3d printer it would actually be better to collect and recycle existing glass – it is typicall very expensive to recycle glass owing primarily to the cost of transporting all of that glass as opposed to just using fresh silica. There’s also the brand management concerns (color matching the glass when using a very wide range of raw materials). The greenest possible way to recycle glass is to do so locally, and there’s an ample supply.

  43. dave says:

    A more poished version with larger lens and better focusing could more properly fuse smaller objects like the bowl. But as far as this talk of structures, it’s hard to imagine it getting more practical than just autonomously pumping out glassblocks all day.

  44. Blue Footed Booby says:

    @Mythgarr and so many others
    It’s art. Do you understand the purpose of art? Hint: if your response includes “that’s not practical” then the answer is no.

  45. IJ Dee-Vo says:

    oh no someone is doing something because he wants to!

  46. Mythgarr says:

    @Blue Footed Booby – I do understand art. I didn’t read the article so that may have been clear there.

    I made an educated guess – that he was trying to conserve natural resources by using a solar sintering technique and a readily available (and easily harvested) natural resource. It was a logical conclusion, but not necessarily correct.

    Even as an artistic endeavor it is very cool – I didn’t think of it so I can’t really criticize it’s creativity. Artistic pieces primarily exist to express something for the artist – maybe they want to convey a certain emotion, or evoke a question for the viewer, or instill an idea. Art exists for a purpose – it doesn’t exist in a vacuum. If the artist was attempting to bring attention to the ‘green movement’ he was definitely successful, although I personally feel that could have been conveyed even better by utilizing recycled materials.

    If this was an engineering endeavor, the technical prowess is impressive. Executing a build of this nature isn’t a weekend project – kudos!

    If this was a “Because I can” build any criticism I could offer really has no effect. They did what they wanted to, and they need no defense (and need not listen to any criticism).

    I wasn’t trying to say that this was a failure, or a waste of time, or anything along the lines. I did what many people with a hacker mentality would do – I looked at his solution and proposed a way in which I think it could be improved.

  47. teowkj says:

    What an ingenious way of obtaining free energy.
    Best of all it is taken from sand which can be found almost anywhere!

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