Hexomino 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 G-hexomino considered here the minimal rectangle has size 9x12 and consists of 18 identical G-hexominoes.

Each hexomino consists of six cubies. So you also can try to built cuboids. Try to fill the following boxes:
- 3x3x8
- 3x4x5, 3x4x6, 4x4x7
More boxes you can find at https://www.math.uni-bielefeld.de/~sillke/PENTA/qu6-G.

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

Puzzle difficulty:
The 9x12 rectangle is of medium difficulty.
If you do not succeed immediately, the tray contains a spare place for one hexomino.

Printing instructions:
Print the tray and 18 pieces of the G-hexomino.
Prints are fine with no supports.
I printed the puzzl