One key dome array means the dome array with only one metal dome(snap dome), this commonly used in only one button or key switches. Below some info FYI
1.The size for metal dome can be 3-16mm, size for the dome array is 2-4mm larger than metal dome size. Usually the square dome array and round dome array are most used. Also your customed design can be accepted, just send us drawings for evaluation.
2.Shape for metal dome, round, four-leg, triangle, oblong all are ok for one key metal dome array, except triangle metal dome with legs.
3.single layer or double layer,white or clear(transparent),it depends on your requirement.
Below are some pics of one key metal dome array FYI. If you still have some questions about it,just contact with us or send us your design for evaluation.