Heptomino Rectification Puzzle

Puzzle description:
The problem of polyomino rectification is to fill a rectangle with copies of a single polyomino. For some of the polyominoes the solution with the mininmal number of pieces needs a quite large rectangle and is surprisingly difficult.
For the P-heptomino considered here the minimal rectangle has size 14x14 and consists of 28 identical P-heptominoes.

Each heptomino consists of seven solid cubies. So you also can try to built cuboids. Try to use some of the P-heptominoes to fill the following boxes:
3x3x7, 3x4x7, 3x5x7, ...
4x4x7, 4x5x7, 4x6x7, ...
5x5x7, 4x6x7, 4x7x7, ...
With more pieces you can fill any box having one side divisible by 7.
Source: https://www.math.uni-bielefeld.de/~sillke/PENTA/qu7-p3

If you can read German: Mehr Informationen gibt es in https://welt-der-geduldspiele.blogspot.com/search?q=3D-Druck

Puzzle difficulty:
The 14x14 square is of advanced difficulty.
If you do not succeed immediately, the tray contains a spare place for o