Extruding (?) from a multifaceted surface

[pierre9QYKY]

Hi there
I'm reasonably competent with Fusion, but struggling with this:

We are trying to 3d print a protective face mask for a child who wants to play soccer, but who needs facial protection, because of a complicated eye condition. The idea is to protect the eyes from the soccer ball, without haing to place lenses over the eyes, as they always steam up, not matter what they are coated in.
I've attached a screenshot of a low poly scan from someone's face, which we are using as a test for this process. 
I want to "draw" the line of the mask on the surface of the face and then extrude that shape outwards to the thickness that I think suitable to create an adequately thick mask.

I can neither extrude multiple polygons in the same direction, nor can I shell the body in order to make the mask.
I'm attaching the warning from the shell command as well.
Can anyone suggest a workflow for this, please?

  

 

[laughingcreek]

you might get there eventually with fusion, but it will be tough.  the high facet count of a converted mesh will bog fusion down.  fusion sucks at working with meshes.   blender would be able to handle this sort of thing better. 

[laughingcreek]

what will you be printing this with?

[pierre9QYKY]

Thanks so much for the reply. You're confirming what I thought. I work in Cinema 4D, so similar to Blender and, yes, I know I wouldn't have any problems dealing with the mesh in there.
I'm using a standard FDM printer, probably with PETG.
This is just a test to help the family, who've been told to expect to pay £1000s for a custom mask.

[Warmingup1953]

Have you tried using the Smooth command (to varying degrees) first??

[TheCADWhisperer]

@pierre9QYKY 

Can you Attach the original stl file here?

I think you could fix this up in free Autodesk MeshMixer.

[laughingcreek]

@TrippyLighting has a video tutorial for a workflow that might work for this. (tagging him so he can provide a link)

basically the work flow would be

-convert triangular mesh to a quad mesh .obj (with something like instameshes or the like)

-import quad mesh into fusion

-convert quad mesh to T-spline in fusion

now you have a T-spline you can further edit directly, or use the resulting nurbs surface.

[TrippyLighting]

@laughingcreek thanks for the tag.

@pierre9QYKY if you are familiar with Blender or C4D then you may want to remesh ore even (manually) retopologize the scan. I am assuming the base geomtry is a scan?

Blender has a builtin quad remesher that might do the trick.

Once you have a quad mesh in Blende, you could apply a solidify modifier to thicken the mesh and then 3D print it from Blender directly.

If you need to make modifications to the mesh you can export it into .obj format, import it into Fusion 360 and convert it into a T-Spline and then work with the normal modeling tools in Fusion 360.

If The quadriflow remesher in Blender does not work, you could use InstantMeshes. I created this tutorial a few years back:

[pierre9QYKY]

@TrippyLighting and @laughingcreek THanks you so much for the help. I really appreciate it and so will the family.
THat's far more comprehensive than I could have hoped for 🙂

[pierre9QYKY]

Hi @TheCADWhisperer, attaching the stl here. Thanks so much

[hfcandrew]

If you have a mesh, use meshmixer. Does not get bogged down, and directly edit the mesh, no conversions or limitations.  I took a look, I can whip this up in a minute for you in meshmixer, I'll post a vid too. However your .stl is not scaled, or the units are wrong:

Right now your model is reading at 12mm wide.

[TrippyLighting]

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@hfcandrew wrote:

 I'll post a vid too.

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That would be great!

[pierre9QYKY]

Thanks so much @hfcandrew , that's amazing.

Yes Meshmixer is the way to go, for sure.
As for the scaling, I guess I'll either have to use a scanner that captrures the scale, or get the subject to hold something that is of a known length and calbrate later.

[pierre9QYKY]

Probably a terrible thing to ask in this forum, but is Meshmixer available for Mac? The website seems to say no

[hfcandrew]

Ya Meshmixer has unfortunately been abandoned (is no longer supported) by Autodesk, and they took the Mac version off the website for some reason. Can still find it via varous webarchives though:

https://forums.autodesk.com/t5/meshmixer/meshmixer-3-5-mac-installer-no-longer-available/m-p/1102552...

You should not have to use any known length calibration work flows, but yes that is an option, typically only needed for photogrammetry because all 3D scanners should scale things properly. What scanner are you using?

[TrippyLighting]

I assume the Mac version was removed, because it only runs on Intel macs but not the newer generation of macs with Apple’s own silicon.

[pierre9QYKY]

@hfcandrew I'm using Scandy pro for iOS. We're hoping to use iPhones as we're on a budget and they have standardised cameras, as opposed to the android offering.

[pierre9QYKY]

@hfcandrew and @TrippyLighting, I'll try to get hold of a PC. So unfortunate that such a cool app is unsupported.

[hfcandrew]

The iphone has a fantastic 3D scanner, so that's fine but the scandy app sucks. I like EM3D. I use it for orthotics and prosthetics. Its like $7 for lifetime unlimited exports.

You don't need a PC for Meshmixer, just download the Mac version I linked to.

I'm guessing your scan was saved as cm, so I just changed the units to mm, not sure of the trim lines you want either, but see attached.

[pierre9QYKY]

@hfcandrew you are being very excellent. Thank you sooooo much.
I'll use the app you recommend and download the old version of Meshmixer.