Sandblasting is a little extreme. If you were to do it, I think dismental the LCD casing and just blast the top cover panel. My wife has access to the equipment but not the skill for an even matte look.
I personally would suggest getting a matte spray can. Alsa corp makes ‘soft touch’ paint coating. Think Audi/VW cars that has soft touch plastics. They make a clear coat spray can that is sold in US and by their Dutch wholeseller (I think). The can should be much easier work than mixing their raw coat with solvent and rent a spray gun/pump. The clear coat should work very well for a matte finish with added bonus of a soft touch rubbery feel :-).
I’ve been thinking of doing that to my white MacBook. Soft touch white rubber…hmmm…