generating internal support

[roykirk]

I'm trying to print a model of a human face (from ears forward to nose) using S3D. I want it to be completely hollow so I can cut out the back by hand and have it sort of be like a mask. I've already had good luck doing this by printing it "standing," with the chin on the build platform and using 0% infill. The only thing I don't like about this is my printer's max Z height is such that it significantly limits how big I can print the face. So my idea was to print the face "up" on the platform, which gives me quite a bit more size. The problem I run in to now is that when the build starts to get to the cheeks and on in to completion at the nose, it starts to sag and have other problems because of the overhang with no internal support.

S3D will not let me manually place internal support, even when I use another program to open a hole in the back of the model. I don't want to use some slightly elevated infill because I find infill a lot harder to remove than support columns are. There's probably a really simple way to do what I want and I'm just not seeing it. I don't have a CAD program such that I can manually create support within the model either. Suggestions?

[jimc]

so from your description this face model has an actual back on it? if so you need to shell the model which requires a cad program. can you please post the file so i can take a look at it?

[roykirk]

Hi Jim - I was about to post the model earlier today but then I figured it out on my own. Yes, it had a back on it. What I ended up doing was using Meshmixer's "solid" tool (I found it makes it easier to select specific areas). I then used the select/lasso tool to cut out the back of the model. After that I went to select>edit>offset and set distance to -0.4 mm and checked the "connected" box. This perfectly closed the mesh in a mirror sort of fashion against the inside face of the model to make a mask, just like I was looking for (and one that will print with interior support as well). I'll attempt to attach the finished STL below: