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Hollow Option


I would like to suggest you please integrate Hollow option, which is very useful option i don’t know why its still missing from Preform.



Been discussed a few times already. IMO, Preform is a slicer, not CAD software. Modifying the mesh to hollow something out or make holes in it for drainage should be done in CAD and not the slicer…

Yes, Preform is a slicer, and EVERY SLA based slicer out there has the function. Please remember that a lot of folks are NOT CAD operators/designers. The want to print something, not have to re-engineer it.

I use Solidworks and I still find the simplicity of a 1 click hollowing function extremely convenient. There are a lot of times when the Solidworks “shell” function fails to work, but my slicer (ChituBox) has no problems hollowing out the part .

Hollowing objects out for SLA printing is a necessity. Forcing people to learn CAD or some other mesh manipulating software to do this, is simply bad practice.


I would agree if the target demographic of FL’s market was consumers/hobbyists, people who just want to print something and have no CAD skills. But FL’s target is “technical” users, people who are using the printers to prototype or make functional models of products (or dental, which is it’s own separate “vertically integrated” market segment) and by definition have the tools and knowledge to hollow or vent in the same program they’re using for modelling. Investing in the implementation of complex functionality that their target market doesn’t necessarily need or want would IMO be a poor decision on FL’s part.

Totally agree with you. :slight_smile:

The thing is if we are purchasing Formlabs printer and using there slicer software then why would i use other software just to hollow the mesh. it doesn’t make sense to me.


If all you’re doing with the printer is printing stuff that you download off the 'net, then yes, you’re right, it doesn’t make sense.

But the printer isn’t targeted at people who are looking to use it like a simple Star Trek “replicator”, who just want to print stuff other people have designed. It’s targeted at engineers who are printing prototypes of the designs that they’ve developed using CAD software. So the people the printer is targeted at don’t need a slicer that hollows things out.

I’m a hobbyist, so I use my printers to print stuff I design. I use CAD. If I want my parts hollow, that’s where I hollow them - while they’re being designed - where I have absolute control over how the hollowing occurs. If I want drain holes, they are trivially easy to place, and in my CAD software I can be sure they are exactly where I want them to be (one of my tricks is to use through-holes that will ultimately take a machine screw to hold an assembly together. So I don’t have any extra holes in the finished print. But doing this means the holes have to be exactly in the right place. There would be no way to do that from within Preform). So adding simplistic CAD features to do these things to Preform would be, in my view, unnecessary “bloat”. Users like me would never use the features.

I don’t think I’ve ever just downloaded something from the internet and printed it. :slight_smile:

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As I may have previously mentioned, I’m a hobbyist and I also design and print prototypes of various enclosures for the computer company I work for.

I’m not sure what CAD program you’re using, but in my line of business Solidworks is king, and I can tell you for a fact that Solidworks can’t always shell an object, especially complex ones, or objects that have been joined (booleaned) together. It simply fails with an error that says the requested function failed due to “geometric conditions”. Sure, I can spend a few hours retracing what I did and figuring it out so it can successfully shell the object, or for printing purposes I can simply export it to STL or OBJ, import it into my slicer, click hollow and be done in 10 seconds or less.

Moreover, hollowing out an object is a SLA “thing”. It’s usually done for the purpose of helping save resin, and help with overall printability. But if the object you design will eventually be sent to manufacturing (mass production), more often than not, it needs to be solid. Based on your reasoning, I now have to make 2 versions, one that is hollow, for SLA prototyping, and one that is solid for mass production.

I’m sure you can see how having a hollowing function would help the flow process for more than just “hobbyists”.

Last but not least is the placement of the vent holes. Desiging a vent hole into an object assume foreknowledge of the objects placement on the platform. By this I mean that in order for the vent hole to be effective, it needs to be at the bottom (or near the bottom), where the model starts to print.

If you put a vent hole some place on the model with the sole intent of hiding it, then you will be forced to orient the model so that the hole is near the bottom, and that orientation may not always be the preferred orientation for many reasons.

Being able to orient your model on the for best surface quality and printability should be the first concern, then adding holes “in situ” is the desirable way of doing it, not the other way around.

One more thing, if a function like Hollowing is aimed at the “hobbyist market”, why is it that high end professional printers like Stratasys have built in software that has these features and more?


:smiley: LOL why everytime you are discussing about CAD. i am saying if we all are paying for there awesome 3d printers and software then why would i pay for CAD or other software.




Making the software easier to use by including a feature common to other software is good, if it improves the user experience.
Making software that is not user friendly may limit market share to CAD professionals.
Formlabs sells their equipment on the basis of ease of use, online tracking, one-click setup, material management, etc.
Therefore the software should have this feature for the benefit of both Formlabs’ product image and market share growth.

CAD is not my core strength, but I need the professional print quality of the Form 3 for my business. Saying anyone who isn’t a CAD jockey is an amateur/hobbyist does not reflect the real world use of these machines. I would use this feature, and I am most certainly a professional user.

This feature definitely gets my vote!


Hollow prints either need to be orientated correctly (with opening facing the build platform), or suitably placed vent holes, to allow any trapped air to escape and allow the resin to achieve the correct level.

Hollowing parts (outside of CAD), especially if required in an assembly could lead to fit/function/deformation issues.

I agree that “shelling” should be done in CAD.

Maybe a “professional” resin based 3D printer is not the right choice for you?

In my opinion, FormLabs is up there at the top of the list.

And as usual, Formlabs will ignore this topic. :man_shrugging:


No, no, no. You have plenty of Form customers here who would very much like such a feature. Dismissing them just saying that they’re not the right users is mind boggling. Even non hobbyists would benefit from the ability to easily make parts hollow, reorient them, change the vent holes within the slicer. That’s why even Stratasys has such a feature. Having to go back and forth between CAD and Slicer while nailing down just the right orientation for a print is an enormous waste of time. Ignoring great features that have been implemented by competitors at both high end and low end would be a mistake.


Well… FL has sold many 1000s of printers over the years since the Form1 was released. In spite of what is almost certainly a very large userbase (there are 12.1K users registered on this forum) there are only a few instances of users who’ve said “I want Preform to hollow and vent my models”. A dozen cases, for example, would only be 0.1% of the userbase, meaning 99.9% of the users could care less about this kind of feature… So I would argue that yes, yes, yes, only a few Form customers would very much like such a feature. :slight_smile:

I’ve been a FL customer since late in 2014 and I have never wanted such a feature.

There are literally more than 100 threads that deal with hollowing, and requests for this feature going back to basically the beginning (2013). back in 2017, Formlabs (Frew) made this statement

> FrewFormlabs
*> *
> Sep '17
*> *
> This is something we’re considering but we’re also wary of inflating the capabilities of PreForm and raising the learning curve for new users. In many cases, it makes sense to modularize tasks like this; containing mesh modifications in programs like Meshmixer and print setup in PreForm. Our strategy thus far has been to educate users on the various tools that can be used for mesh modification and make PreForm the best it can be for print setup. We have a tutorial on hollowing parts in Meshmixer if you’re interested.

That was then, when the playfield was still in Formlabs’ favor. Since then, other software became available which left Preform in the dust in terms of features and function. Those arguments Frew tossed in at the time no longer hold water.

But the reason why you don’t see a lot of 'traction" is because a lot of folks have gotten so used to Formlabs saying NO, that they don’t even bother.

That was the case a while back when folks were asking for a means to mirror an object in Preform. Same push back, same arguments. But eventually they relented and now there’s a mirror function. Who know a year or two from now, the hollowing out function might appear on Preform.

But by then, who know how many potential users FormLabs would have lost

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This is like we need two refrigerator one for water bottle and one for ice cubes… which is senseless again :smiley:… Hollowing is a very useful option and i hope Formlabs will add this in near future BECAUSE I DONT WANT TO USE CAD LOL, ZBrush is enough for my work

100% agree, need hollow :star:
When you use an ink printer, In your print software you have plenty option, in fact everything you need, (black & white, color, resize…) so no need to go back in photoshop, illustrator, indesign… Why? Because your software is complete.
So yes Preform need to be completed.


You can do all those things in Preform - choosing resin type is like choosing ink color. You can resize and rotate your artwork before printing. But if you want to make more complicated changes to your artwork, like changing shapes or positions of portions of the graphic, you have to go back in to Photoshop to do it. Because your printer’s software isn’t editing software, just like Preform isn’t editing software.

Preform is already as-complete as your analogy.

I don’t understand why do you have problem with Hollow option ? creating software is not an easy job and they have created preform means they can create hollow option too its not that complicated thing for them. I just want to save resin because its not cheap.


Because I’m a software engineer and IMO it is a complicated thing to implement.

There are many other improvements to Preform and Dashboard that could be implemented first that would benefit a much larger percentage of the userbase. I would much rather Formlabs invest their resources in things that benefit that broader swath of the userbase than the implementation of functionality that already exists in other software.