This achievement requires that you make a snap conforming to each shape outlined in the Achievement menu and is cumulative across all rounds. In total there are 56 shapes you must create with multi-snaps. Many of them will come without trying over time, but several of them will require real thought. Most of the shapes can only be placed on certain board configurations. Once you eliminate a good portion of them from natural play, start knocking them out one by one. The first step is determining if a shape can be made on a board. If it can, then you need to create the words to fill that specific multi-snap shape.
The first photo below shows all of the shapes, with the most difficult ones circled in red and numbered. All shapes start in a grey color and turn blue once you find them. The subsequent photos shows the best (and in some cases, the only) way to form the shape on a board. You will need to dedicate numerous games in their entirety to finish off all of these shapes. Keep them in mind as you play and remember, only the tiles that flash green are included in your shape.
These can be tricky mostly because you need to create two side-by-side 4-letter words that also need to align properly to create four 2-letter words. While this is at least possible on most boards, it is difficult. The easiest method to obtain these is to wait for a specific board configuration that occurs periodically (but somewhat rarely) where two words will align directly beside on another, as shown in the image below. Here, half of the battle is already won for you. The black words are the only words on the board at the start. You only need to worry about placing four letters correctly to complete the shape.
This shape is a complete 3x3 square. This is also tricky as you need to be quick on your feet to come up with the combination of words that works. It cant be placed on all boards, but it can be done on about half of them. You only have seven tiles in your rack, so you must incorporate at least two default tiles into the shape. The easiest method to obtain this achievement is to again wait for the configuration from Shapes # 1 and 2. In this case, two thirds of the work is already done. You only need to find a place to put three tiles. See the image below for an example.
This is probably the most challenging shape to create of them all, for two reasons. First, board configurations where this shape is even possible to create are rare. Secondly, you need to be a master to prepare four interlocked 3-letter words to complete the shape and it even requires some luck. This shape can only be created on wide open ends of board words. See the example below. Basically you need to use the final letter in a word as one piece in the shape. It can be a corner of the shape, or an internal piece. Then build your circular cluster of words to complete the shape.
Follow THIS link if you are having trouble with any shape. The developers have posted in their blog to help all of us out with each shape!