Have now (finally) get up the track. Certainly not for the faint of heart, as the frustration potential is extremely high especially in the loops. However, the joy is for the success even bigger. The individual parts are well made, the assembly instructions could be more detailed, but with a little imagination it is "readable".
Conclusion: Those who like tinkering, not of the first failures (straight liefs still ..) can strike back, will have lots of fun with the ball roller coaster! If it is then thought about it then again more tags ...