3D printing - Extrude entire model?

nickdk

hello everyone!

I'm trying to make a model ready for 3D printing but I don't know how to make the model hollow to save cost as shown here in their tutorial:

http://www.shapeways.com/tutorials/creating-hollow-objects

I have attached my SU model and as you can see it's more complex so i have no idea how to solve this, I have tried to copy the model and scale it down to make a "smaller" version within the outer faces but it didn't work, maybe there's a plugin that can help me out or just some of your expert guidance

I have a made a "hole" in the top of the model as a test but that wasn't enough. They recommend a wall thickness of at least 2mm
Beside this The model is tested and is accepted for printing but the cost is too high due to the large material volume usage, so If I can make it hollow it would be great.

I hope you can help me as I need to get this shipped ASAP :S

3dprint_10_test.zip

TIG

Couple of points...
Your model is very small and you unit settings prevent you seeing any small dims as they show as ~0.0mm - change to mm AND scale your model up x10 or more while working as Sketchup/OpenGL have problem making very small faces [<~1mm] - but fortunately no problems with having small faces, so if you scale down again at the end it'll be OK.
Your model also had 6 problems which were fixed by using 'Model Info > Statistics > Fix Problems...' [probably resulting from the small sizes of some geometry].
If you group your geometry then 'Entity Info' then in v8 if you select it it'll show it as 'Solid Group' IF it's manifold - i.e. a proper solid; if not its shows as 'Group'.
To test this make a simple cube and group it - it's a 'solid'.
A 'solid' can have no internal partition faces - visible in XrayMode or using a SectionPlane - remove these.
To test this edit your cube group and copy the cube using Move+Ctrl to make a copy physically separated from the original: it still reports as 'solid'. Now move one cube and snap a face to one in the other cube so that there is now an internal 'wall' - now its reports as being a non-solid!
Erase that internal wall and it again becomes 'solid'.
Your model seems to have none of these 'partitions' BUT still reports as non-solid! So why is that?
Well it's because parts of it meet at a common edge, so two distinct volumes share an edge - this is also a cause of a form being non-manifold.
Again to test this edit your single cube group and copy the cube using Move+Ctrl and snap the bottom edge of the copy to the top edge of the original - it now reports as non-solid despite there being no internal facets!
This is because in the 'real world' you can NEVER have two cubes meeting at an edge 'exactly'. An 'edge' always has two faces - it can never have more or less as then it's not 'manifold'. So the two forms will either have a very very small gap between them [thus they are two 'manifold' parts of the whole] or they'll overlap very very slightly [and therefore form an internal partition, making the assembly non-manifold; unless that internal face is subsequently deleted, so that then you have a single manifold form again].

Your form has many such 'shared edges' and is therefore non-manifold...
You can resolve it two ways...
Make a tiny gap between the forms so there are then two edges - i.e. one edge for each pair of faces, and not one edge shared between four faces.
OR
Overlap the two forms slightly, so again there are ensuring the small internal face is deleted to maintain manifold-ness.

So the simple rule is for an object to be solid [manifold] all of its edges must have two faces - no more, no less...

nickdk

Thank you very much TIG, there's a LOT of information to digest, I'll get back when my mind has understood it all

Just to be sure, the problem with the manifold you refer to is that in regards to the hollow structure I would like or the model as it is now? I have uploaded the current model and their backend system said it was ok and "printable" so I assume the manifold issues are in regards to adding wall thickness?

Thanks again!

TIG

A 'solid' [or manifold] group/component is needed to perform boolean operation [trim, add, subtract etc].
You may well find that as it stands, with no internal partitions but with some edges 'that do not have just two faces', it will work with conversion software for some 3d printing companies... however, it will still fail when doing boolean operations on [or with it] in Sketchup because it's not regarded as a proper 'solid' because of those rogue edges with 4 faces...

nickdk

I follow you,

I'm not very familiar with the solid tools yet, I'll have to explore those. I understand from your guidance that I need to fix the model according to your guidelines before I can use these tools to create a wall thickness.

Thank you