Puzzles Galore

Tim has a large number of puzzles in his toy collection, and here he showcases just some of them.
Starting with Oskar's Maze - a puzzle that was originally made of plastic and is now made of metal, puzzling dice and Chinese Rings, an old puzzle made from Bakelite - a precursor to plastic, Tim's own Rubik's Cube - signed by Ernő Rubik himself, an amazing puzzle calculator where the keys remember which number they are supposed to be even though you can move them around, a magnetic puzzle that came from Freddie Laker who was more famous for pioneering the idea of a "no frills" airline business model in the 1960s which many companies have adopted in the years since then, an entanglement puzzle based around a pottery dragon, a Japanese puzzle based around 4 clear trays (or are they plates?) which can be both rotated and also stacked in different orders, a skill toy that can knot itself, a couple of German sliding block puzzles, a ball bearing maze that is especially good for travellers, three puzzles from Toyo Glass in Japan, the Swinging Swami puzzle (which came out in the 1980s), a couple of puzzles from the 'I Love, I Love' company in Belgium...
... and finally reveals the answer to a problem he sets at the beginning of the video. What is the purpose of the strange black object?