It's a challenge to assemble. Takes quite a lot of building skills to get it all working. Some parts are very small and are hard to handle. But this is what makes it a fun project. Take your time and make sure you get each step per the picture. Make sure each joint is secure. Laser cutting of the parts it the best I have ever seen. Once completed it takes a little fine adjusting to get it all to work. Most errors are due to a loose joint. Some parts are easy to break so be carful. Once completer it is fun to operate and watch the marbles run.
It is very entertaining and a good way to spend 15 to 20 hours putting it together. The instructions are pretty good and usually very clear with an occasional drawing that take a magnifying glass to see the detail clearly for an older person.