Question on 3D printing option

Guys how do you name this 3d printing option where instead of printing the whole solid body volume, it makes an internal triangular grid/mesh/porous structure inside in order to save material?

Thanks

You cannot just 'name' that you want the model hollow as an option. You have to create the model as hollow.

And let the inside become part of the outside world with a hole of some kind

The name you're looking for is "infill" or "scaffolding", depending on the software or printer that you are using.

Infill is normally required for FDM printers, and none of the Shapeways printers are based upon FDM.

The Shapeways printers themselves do not require Infill, but you may opt to add it to your design anyway so that your object is stronger.
It's entirely possible to make a completely hollow object with the processes that Shapeways uses.