Create PCB holder from a PCB. Basically we generate cubes around THT parts and cylinders at mounting holes, subtract it from a surface and then the PCB can be laid onto it. Contrary to supporting only at mounting holes, the PCB is supported on the whole area.
./box.py board.kicad_pcb > diff.scad
When stdout is a tty, it shows a plot of the board.
In OpenSCAD:
%union() {include <diff.scad>}
Presumably you want a difference from a big cube/other surface, see example.scad.