A little tricky!
As Visuhole makes a perfect Drill, Carve, Emboss..
Scale your object, scale your Stencil
Apply Visuhole for the groove
And Slice! (With Su_Slice by Suforyou)
[image: tPuV_GIF_visu_slice.gif]
Maybe some Guide lines will be necessary...
[image: Kfy3_GIF_visu_slice02.gif]
Will be the same for your mountain surface!
[image: zxg5_bloc.jpg]