Snap Locking Mechanisms in a Plastic Enclosure

i want to know will a deflection of 0.75mm will give a good snap locking mechanism for a force of around 100gms. it should not be very weak also. is there any guide for snap locking mechanism where a snap technique is used to lock a probe or anttenna suppose in a plastic enclosure at the extreme positions i.e., locking at fully retracted and locking at the fully extended position. what material would be suitable i have zeroed in lexan FL900P but is there any other material with better properties for impact, elevated temperature and regidity. Also what would be the force which will be practical for such probes used in handheld enclosure. please help.