After 3 months and 500 fails, Kaplamino managed a perfect marble run with magnets and chain reactions galore. On YouTube he adds:

 

Since magnets and marbles I’ve always wanted to make a big chain reaction in one take with this 2D style! It’s also a “one marble path” which means you have to follow the same marble for all the tricks (in that case the little blue one.) Because everything is in a tilted plane, the hard part was to find different ways of having the marble riding up along the table (magnets, falling weight, catapult …).
 
To do that, the marble has to be light. And because everything has to be triggered by this little marble, all the tricks are very unstable. Most fails happened when an element fall down earlier than expected. I learned a lot about chain reaction, and I discovered the amazing power of the hot glue gun!