i CAN not believe that you are the 1st person to discuss this... this must be fairly new to some people ... i was surprised.
encapsulation is also referred to as the water globe...if you will...
when i and my class did one the other day we used clear tips... 1, the size of the nail it will be placed on and the other, 2sizes smaller so that it fits facing the other tip, in opposite direction,,,so that it forms a bubble... then you seal the sides and bottom with gell... i suggest a clear gel, simply because it's cleaner and clearer... then you fill the inside with glitter or rhinestones..or pictures.. or trinkets.. along with water then you seal the other end. and it forms this water globe. or encapsulation