Wonder Puzzle 16 by Mitsuhiro Odawara

Puzzle description:
Wonder Puzzle 16 looks like an easy pentomino puzzle, but it has an additional magic twist: Here, the pentominoes consist of rectangles instead of squares. 
First problem: Put the three pentominoes into the tray so that they form a 3x5 rectangle. Only one solution.
Second promblem: You have an additional small rectangle. Now fit all four pieces into the same tray! Again, only one solution.

This wonder puzzle was designed by Mitshiro Odawara in 2013 (https://torito.jp/puzzles/hako068.shtml) and is presented here with his kind permission.

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

Puzzle difficulty: 
The first problem is easy, and the relatively large clearance is essential for problem 2.
The second problem is difficult until you find out where the additional space comes from.

Printing instructions:
Prints are fine with no supports. 
I printed the puzzle in PLA at 0.1 mm layer height.
The STL files were generated using PuzzleCAD: https://www.thingiverse.com/thing:3198014.