Hi jetblast, right now one of the problems you're having is trying to put the blend into a fairly constrained small amount of area.

Blend wants to adapt itself to the surfaces on each side of the blend. When there is not much space available it will cause the blend to buckle as it tries to violently and suddenly switch its shape in a small amount of space.

You'll probably want to make the hole to be fairly larger in size on the main body.

- Michael