Good Morning, all...

I have been generating a number of solids for 3D printing with excellent results from
.stl files from MOI. However, many of the service bureaus quote based on cubic
volume of the solid. In most cases it is not necessary to provide a solid and I could
receive the same results from a hollow pattern. Is there a way to change a solid
to a hollow and define the thickness of the remaining sides? For instance, if I had
a model car that was created as a solid, can I later change it to a hollow with the
sides 1/16" thick and generate a .stl file from the results? I union many individual
solids which is much easier than creating the hollow initially. Thanks

Hi Bob,

If your geometry will alow it, have you tried the shell command?

Michael T.

Good Afternoon, Michael...thanks for the link. I'll check it out. Since most service
bureaus charge by the volume of material used, it would be a money saver if I can
create only the outline. My horseshoes typically use 9.75 cubic inches of material.
Providing only a hollow version strong enough for casting should reduce volume by
50% or more....Regards...Bob

Hi Bob, like Michael T mentions you can use the Shell command to make a hollowed out object with a constant wall thickness.

But if you have a complex object like an entire model car made up of a whole bunch of little surfaces, that is probably not going to shell successfully though because shell is a pretty complex operation that does stuff like build offset surfaces and then extend, intersect, and trim them automatically. That process gets pretty difficult when the model is more complex.

However, another method you can use to make hollowed out areas inside of a solid is the Boolean difference command - create something like a box or sphere and place it so that it is contained totally within the model and does not touch any of the outside surface of it. Then select your main model, and run Construct > Boolean > Difference and then select the interior part as the cutting object. That will carve out the interior shape as a void region within the solid.

Also see here for some tips on how to select objects that are contained inside other ones:
http://moi3d.com/forum/index.php?webtag=MOI&msg=1810.2
http://moi3d.com/forum/index.php?webtag=MOI&msg=3324.4

- Michael

Hi Bob - so one of those horseshoes with text engraved on it will probably not shell successfully because it will try to process all the little pieces of text as part of the shape.

You'll probably want to build a kind of simplified shrunken down shape for the inner core, then you can carve that out as a hollow region using boolean difference.

- Michael