Is it easy to turn a Laser pointer into a pressure switch laser?

As the title says; how easy would it be for me to turn my laser pointer into a pressure switch laser.

Not very. Pressure switches are built to have either air or fluid activate the switch. So for you to make it a pressure switch you would have to waterproof the switch assembly on the laser pointer and then glue a tube over the on off switch. If you need a certain pressure to activate the switch you might have to make a diaphragm assembly over the switch before you mount the tube. Then you also might need a way of varying the pressure requirements that activate the on off switch.

Unless you were in a survival situation or MacGuyver shows, it would be far cheaper and easier to buy a pressure switch that also includes pertinent data that activates the switch and fluid flow and such.