After Ashley Vermeersch put a lot of effort in convincing us to use his idea for a new competition, finally here it is.
Create a flat shape with a complete set of pentominoes.
Choose any pentomino and use 12 copies of it to surround the shape you just created. All pentominoes must be placed flat, in the same plane as the shape with the complete set of pentominoes.
The outer shape must
completely surround the inner shape and each pentomino in the outer shape
must touch the inner shape somewhere, where just touching in a corner
doesn't count. The total shape may not contain any holes.
Try to maximize the outer perimeter of the outer shape.
In our example it is 82 units of length.
The following example is not allowed, as the inner shape touches the space outside the outer shape in a corner.
A useful aid for searching a solution is the program “FlatPoly2”.
You can download it from the homepage of Aad van de Wetering from Driebruggen, the Netherlands.