This is called the Not Too Hard Box puzzle because it is neither too hard to solve nor too hard to make. I made one on a weekend morning.
It consists of six pieces, all of which are different, that must be assembled so that they fit together as the six sides of a box. Each edge of each piece has either a slot or a tab. You will notice that there are only six possible different arrangements of slots and tabs around the perimeter of a square. So only six distinct pieces are possible; the six pieces of the puzzle represent the entire set. An interesting thing about the puzzle is that it requires six pieces, and the rules for making pieces yield exactly the number required. I think that this is characteristic of a certain set of puzzles.
Piece #1 has no slots and four tabs. Piece #2 has no tabs and four slots. Piece #3 has one slot and three tabs. Piece #4 has one tab and three slots. Piece #5 has two slots adjacent to each other and two tabs adjacent to each other. Piece #6 has two slots opposite each other and two tabs opposite each other.
About four feet of ½” square wooden dowels. These are available at hobby shops, art supply stores, craft stores, and even hardware stores. Make sure that they are actually square. The puzzle requires a measure precision to work well.
I chose to make my puzzle out of square dowels because they are readily available and glue together nicely. I used basswood because it is not too hard and easy to work.
Some kind of saw to cut the wood into the lengths required.
Some kind of suitable glue. I used 3M wood glue.
Clamps and/or tape to hold the pieces together as the glue sets.