This was my first UGears kit, but likely not my last. I've built about a dozen marble runs from other companies. Based on the parts count, and the small size of the box, I expected this would be a pretty simple kit, other than maybe building the chain. Well, turns out the chain is one of the easier parts. This kit is surprisingly intricate. Some aspects of assembling it are quite tricky, in part because it's sometimes very hard to get your hands in a location where you can apply firm pressure. But also in part because parts tolerances could be better controlled. Many of the parts fit together Very tightly. So tightly that putting so much pressure on them to seat them risks breaking them. (See my build tips section, below.) OTOH, a few parts are so loose I had to glue them so they'd stay together well enough to go on to the next step. In particular, the "Loop-the-loop" wouldn't stay together at all without glue. For the most part, though, I'd say the quality of this kit is better than most of the made in China runs I've built .
On the positive side, the instructions are very good. The drawings are clear and well marked as far as what tabs fit in what slots, and in most cases which direction a piece should face. Possibly the best drawings of any marble run kit I've built. Late in the build, where you're attaching an assembly with lots of contact points the drawings aren't quite as clear, but if you line up the parts that are clear the rest becomes obvious.
None of the runs I built worked 100% after the initial build. Balls would fall, or fly, off the tracks, or get stuck in places they're supposed to roll. I've had to make as many as 15 or 20 modifications to a couple of kits to get them to work 100%. This kit had only one small problem, where a piece that fit too loosely allowed balls to get stuck. A dab of glue and everything worked. Very good design work, UGears.
BUT, after being assembled and used for a few weeks, a couple of things have happened: two of the unsupported marble tracks have sagged, and the marbles no longer roll as freely as they did when new. And the balls are frequently rolling off one section of track. These were pretty easy to fix if you have some scrap pieces of wood (I always keep extra parts, and some of the boards so I can use the wood later.) I've posted a few photos of my fixes.
How did / do I like it? Mixed. To me there are two aspects to a marble run. One is the challenge and enjoyment of building it, figuring out what's wrong, and fixing it. (I almost miss not having more issues to fix ;) )The second is watching it in action. In part, this run is really cool. The way it traps and releases balls, and opens and closes ball paths is a very cool design. Different than I've seen it done in any other kit. But I hate that it's not motorized. I have to pay enough attention to holding it down, and turning the crank, that it distracts me from watching the balls. It would be very easy for UGears to make a motorized version. I've motorized a couple of other runs, so I figured out how to motorize this one, too. If I can do it, UGears can do it. (And probably better than I did.)
Otherwise, I'm not thrilled at how much the run flexes when you crank. If it had a solid base, instead of a thin partial perimeter, it would be a lot stiffer. That problem has mostly gone away with the motor, too.
I've posted a few photo showing how I mounted everything, and a video of it running. Finally, it needs more marbles. The kit says it comes with 10, but three of them are used as counterweights, so you only have 7 in motion. That's not enough to keep the chain hoist full all the time. Oh, and I think the solid color marbles are kind of dull and boring. Fortunately, glass marbles in all sorts of colors and patterns (16mm, or 5/8 or 0.63 inch) are readily available on Amazon and other places, and are cheap.
Would I build another UGears marble run? Yes, especially now that I've motorized it, and the motor will drive the second kit, too. It's got some unique features I haven't seen on any of the Chinese brands, the quality is quite good, and building it was an enjoyable challenge. Not the hardest kit I've done, but also not for beginners. The ability to connect 2 or 4 runs together is very cool, too.
If you've built other runs and enjoyed them, you'll probably enjoy this one.
Presenting the Ugears Marble Run Chain Hoist—an exciting kinetic sculpture and an intricate toy that teaches as it entertains. Turn the handle clockwise to set the machine in motion, and watch as the wooden chain hoist collects and lifts the marbles to the top of the machine, where a 3-way switch distributes them on different tracks. The Marble Run Chain Hoist is modular and can be connected to other Marble Run Chain Hoists (2 or 4 models can be connected, in pairs) using special connectors (included). Attach two Marble Run Chain Hoists together frontally, or connect four together, both frontally and laterally, for a mini system of hoists and runs. 
Marble Run Chain Hoist features:
DIY wooden Marble Run features:
