really tough level, due to the void in the droplet you have to compensate for it. only managed 1 star here.

think rubiks cube

level 10 needs to be done by crossing the lines toward the bottom third of the triangle.
level 11 needs to be done same as above but can almost be in the middle.
level 12 is obvious
level 13 need to be cut into 9 pieces think rubiks cube
14 similar to 11 and 10
16 is quite tough, i went from the flat side on top through to corner bottom right then had to play with the other cut to get it right.

hope this helps