I am planning to replace acoustic ceiling tiles: some will need to be custom cut. The material is reminiscent of press-board and seems somewhat brittle. What is the proper tool(s) and technique (if any) to cut the material to required dimensions?
The default USA maker (I don't know how far they extend worldwide, or who their competitors are locally but they are the only brand that comes to mind for this sort of ceiling in my head) of such ceilings says: Always cut ceiling panels face up with a sharp utility knife.
The maker of your panels suggests the same thing.