How to build simulation box?

Dear everyone,
I want to build this kind of model from the picture,the lower part is from data file,I want to build three part ,the lower one ,the cone,and the final simulation box,however,the final box is just the lower one,how could I build three parts just as I described?
Best wishes,
Jerry.

3364432B@...5395....png

Dear everyone,
      I want to build this kind of model from the picture,the lower part is
from data file,I want to build three part ,the lower one ,the cone,and the
final simulation box,however,the final box is just the lower one,how could I
build three parts just as I described?

please study the LAMMPS manual and the provided examples to learn how
to build or import a structure in LAMMPS. nobody will do that for you.
since you want to build a complex structure, it is best to do this in
stages and test building individual parts separately (and figure out
how to do it correctly) and then combine the steps into a single
setup.

axel.