There are eight dowel segments that you must fit into a box. You should be able to get seven pieces in with ease. What about the last piece?
This very simple project was built from scrap wood (minimal cost) and it took about an hour. STP/STL files are included for those that would like to print a version. I tested the puzzle on my two teenage children and both gave up after 5 minutes so I would say it’s slightly challenging.
Link to Amazon version: http://amzn.to/2hL9gHH
I understand the originator of this logic puzzle was Tesa Timonen of Sweden in 2002. I reversed engineered this version from online pictures.
More Info: https://www.instructables.com/id/Wood-Dowel-Puzzle/