A novel 3-D pattern modulation surface (PMS) using slotline elements is proposed to customize the radio environment. The element structure is simply composed of a slotline printed on a single-layer substrate. By changing the length of the slotline, the reflection phase of each element can be accordingly adjusted while maintaining the reflection magnitude almost unchanged. Consequently, the slotline structure with a reflection phase range of over 360° is used as a key element to design the presented 3-D PMS for modulating incident waves. Calculated and simulated results agree well, which indicates that a reflection angle of 50° is obtained by using the proposed 3-D PMS.