How to create hollow 3d models from 123d Catch

Hello I am an art teacher in New York City and I need some help with an issue getting 3d scans ready to print on shapeways:

About a year ago I uploaded a 3d scan of an original sculpture bust and ordered a ceramic "miniature" of it from Shapeways. I was very pleased with the result! Recently I had a similar bust "rejected" with the message that the model needs to be hollow. My first ceramic print was solid, so I am guessing this is a new requirement? I would also like to print in plastics and see that hollowing out models is a potentially huge cost-saver.

So, I am seeking help on "hollowing out" 3d models of complicated sculptural scans. Is there someone (or a web tutorial?) that can walk me through this process in Rhino3D or Blender, or some other software? It is proving to be more difficult than I expected, but since I have dozens of students (and dozens of personal projects) which I want to start uploading to Shapeways and printing, I really want to get some guidance on this process instead of spending hours figuring it our for myself.

The crux of the problem seems to be that the scans themselves - which I create with AutoCad's 123d Catch - are not formatted in a way that is easy for a computer program to hollow out with automated commands. I have my fingers crossed that someone has experience doing this and can point the way.

Thanks in advance for any help you can give me - screenshot of sample piece attached

simple answer: Tutorial for blender

But as always there are more ways how to do it.

If you have other question, feel free to contact me.

thank you for your reply - I had in fact found that tutorial but I am not too adept in Blender yet so I could not make it work at first try. Do you know of any methods that work in Rhino by any chance? I am using that program more and searching for answers there....

If you use the "Search" option at the top of the Forum page and give it the keywords "rhino hollowing", it should lead you to
this thread which contains a youtube link to a short tutorial video that advertises a new convenience function in Rhino3D V5, but also demonstrates how one would go about hollowing an object in version 4.

thanks, I found that video this morning (it did not work for me because of the complexity of my model - can't just slice open the bottom for some reason) but I will now read that thread and hopefully learn more - much appreciated!

If you have the ability to share the STL model, then there are several helpful folks here that could make it hollow for you.
If for some reason you would rather NOT share the model with the public, then you could PM it to someone, (including yours truly - I'd be glad to take a look)

thank you very much! I'd be happy to send you a copy of it as long as we are clear that I retain all ownership - I am relatively new to this space and have had some colleagues get burned on other sites with people re-selling their original designs, so I'm sorry to have to reply to your kind email with such a disclaimer, but I just want to be upfront about it!

all the best,

Luigi

Take a look at my shop.. https://www.shapeways.com/shops/stonysmith
Unless your item is model train related, then it's not going in my shop <GRIN>

I completely understand your reluctance. <raises hand> I won't copy, share, or even retain your model once I take a look.

If you have Rhino, search for Symvol. It is an add on for Rhino that is free and among other functions it has a very affective a one key press shelling command for meshes.

For anyone following this thread:

@TerraCottaLu had a model that was a item sitting on a base. The item and the base were two separate shells, and using Netfabb Basic to slice open the bottom of the model was only slicing the base, but not the main piece above. So, I ran the model thru cloud.netfabb.com to get it back as a single shell.

Then using Blender, I deleted all the faces from the bottom of the model, and then selected the "Solidify" modifier and set it to 1.0mm

Not counting the time spent by cloud.netfabb.com, the process took all of 2 minutes.

Many thanks @stonysmith and everyone else who has been replying here and also to me privately. Although I first ordered from Shapeways about a year ago I have never been active on the forums and it's been a pleasure to see what a great exchange of support and info goes on here. I can't wait to try out the various processes and report back here.