JMBricklayer Roller Coaster Challenging Building Sets for Adults 70003, Motorized Steampunk Marble Run Great Ball Contraption, Large Dinosaur Factory GBC Machine, Gifts for Challengers(5391 PCS)

I love marble runs. I've built more than a few. BUT, if you buy this, know that it is an above next level expert build!!!In fact, despite my experience I can't even finish the first bag of parts. Sadly, the directions are almost great, but all you need is a few bad descriptions like; 'which hole does this go into', or 'what direction does this piece go', or 'these pieces look the same, or 'the orientation depicted is misleading or not fully described or can't even be determined'. Just one error (and with 5500 parts that's almost innevitable) throws everything off. I've actually shelved it after trying to build a subassembly 3 times and failing. I'll go back to it, but I want you to know this is really really hard and there are just so many ways to mess it up. I will say that the problem rests 95% with the directions. Sadly, they came so close but in the end missed the mark which means all I bought was 5,500 lego pieces. If you enjoy what I've described, then I'd rate it 5 stars. But since there is a pretty high chance I will never finish it, I have no choice but to give it only one star. I've taken pictures and circled all of the instructions that are confusing in just the first few pages of over 100 pages and will send them to the company for their review and hopefully updates.

Very sad. Missing 2 critical parts and cannot complete. Not sure how to contact manufacturer other than this review.