Square Packing Challenge - Brain Teaser Wooden Puzzle

Invented by Professor John Conway's, Cambridge University Mathematician.

The wooden box holds 17 different wooden shape pieces.

The objective is to take all the pieces out of the box, mix them, and then try to put them all back inside the the wooden box.

Once you try doing so, you will see that there is always 1 piece left out and it feels like it is an impossible task, but... you know it is possible.

Can you solve the problem?

Perfect puzzle for the talented puzzler.