Geostatistical R Package - Board

I would like to set up an irregular 3D region to estimate and simulate within. Would you please provide an example of either setting up a 3D grid using perhaps a 3D tesselation (perhaps a DXF file) or alternatively perhaps some sort of masking grid loaded from an external file (with some flag like 0 to ignore and 1 to estimate). I'm not sure it is possible to estimate over a grid that has irregular extents? It seems possible in some of the 2D examples I've found on the web but not sure how to set this up in 3D, please.

Dear.
I confirm that RGeostats can build a selection from 2D polygon only.
Masking/Selecting 3D samples of a database from a 3D region must be done using another R package.