Sink fold
There is a fold in Origami called a sink fold where you have a point and you push it into itself, and then there is a reverse sink where you pull/push it back out well not all the way, that would be the equivalent of not doing it!
If you try you can get several levels of in and out and it’s not limited to four point eight sided objects.
Hexadecagon or Octagram with a sink and then a reverse sink
Things to consider: -
Some things are easier said than done and you don’t really just push the point in you have to partially unfold the structure to get it to fold and take up an organised and inverted shape.
In Origami they talk of collapsing the structure into shape having made the preliminary creases with the work essentially unfolded. This is where I need to be more careful and consider what I am doing with pre-creasing. Sticking more rigidly to Mountain or Valley assignments for the creases, not flexing them both ways.
Also lessening the amount of flexing will protect the vertex in the centre of structure there are a lot of edges meeting there and it is easy to tear it.
