I would recommend you watch a video before building which shows important techniques. I was impressed with the precision cuts of the pieces and if joined properly should perform as shown. DO NOT glue along the way since disassembly at times may be necessary to correct misalignment. Breakage was minimal but if it happens then glue is necessary. Probably not for someone with big hands or fat fingers. I found it helpful to de-bur the slots and holes with a small craft file or sandpaper before fitting to allow the pieces to join more easily, or you run the risk of applying to much pressure and breakage. My assembled machine has one small glitch with the seesaw not working as it should and I have no clue what is causing it. Ah ha, I figured out the ramp leading to the seesaw needed a little more angle so the marble had enough speed to tip the seesaw so I simply added a spacer to one of the feet.

This was a lot of fun to assemble. So much so I want another one. Directions are easy to follow and they give you spare parts. I really enjoyed putting this together.

16 yr old grandson loves building things. He enjoyed putting this together.

The engineering and design are flawless. The components and directions for assembly were spot on. I do recommend that you have super glue handy; I broke a half a dozen small parts as I pushed too hard. Clearly my fault and it did not impact function. When finished the steel balls moved around all the paths as designed.

Good puzzle/toy. Really good non word instructions good help with tough QR code help videos. It was VERY helpful that they gave you extra pieces knowing that I would break them some where hard to attach. The overall great laser cutting and assemble they had done amazing.

I bought this as a gift for my husband. He really enjoyed putting it together, though he had to re-do several bits. You must have patience, and good eye for detail to do the best with this item. It was really cute once he put it together. Took him about ten hours all totaled. Would buy this type of item again, in fact, I chose a different model for his birthday...shh... it is a secret...LOL

It took a few days to build and it was a bit tedious. Came out real nice! My husband was pleased.

enjoyable project with great instructions .

My husband has a laser machine and wants to make things like this, so this was a great way for him to learn how small, intricate pieces can fit together. Sadly, when it was all assembled, small errors in some pieces prevent it from working properly (the marble is supposed to be able to follow the tracks, and instead always gets stuck.) That said, it was still fun and informative, so we will give it 3 stars.

I really enjoyed putting this kit together , altho the pieces are very thin an fragile it definitely requires a lot of patients and care putting together . I found the use of needle nose pliers necessary to press many of the parts together to avoid breaking them . Even though they say no glue is needed , foresight tells me many of the parts will come loose before its completed , so I used small amounts of wood glue on most of the joints pressed together . Especially on the tracks an rails , wasn't necessary for the steel pins . Also needed glue on all the steps to keep the spiral track in place , once completed everything worked fine , works best on a level surface . Fun project if you take your time , but probably to fragile and complicated for younger children , some of the directions are a little vague and not quite clear .

Gave to teenage granddaughter who is almost finished building it. Assists in teaching following directions. She is an A student and was able to do without assistance

When we went to build. Found the balsa wood crumbled no matter how much care was taken... sent it back too!

Ours work with one dead spot in the design. You really have to think ahead on this one. But it was a fun project.I would recommend it!!!

Love this puzzle. You have a great toy to play with when your done.

I got this for my 24 year old son who is a mechanical engineer. It was a great gift! He enjoyed putting it together and it looked really cool when he was done.

I enjoyed assembling this puzzle and then using it. The puzzle has clear pictured instructions that for the most part are easy to follow. This has some small parts that are not easy to install in places, but overall I did not run into serious difficulties. The parts came off the boards easily. Although I tried to be very careful, I did manage to break three parts during construction, that I used glue to repair. I am very pleased with this puzzle and do recommend it. When finished it must be used with caution to avoid damaging it.

My husband is an engineer, and he loves all things mechanical. I gave him this 3 D puzzle kit for Christmas, and he couldn't wait to start working on it. He was absolutely glued to his chair in the den having pieces and instructions all over his desk. He finished in about 3 days, and he loved putting it together. He was so proud of himself when he showed me the finished product, and we watched the marbles go round and round. It's a super kit, but it isn't for a young child, and there are lots of little pieces in the kids.

I bought this as a gift for my wifewho loves craftingand my sonwho loves marble runs. She devoured it over two evenings putting it together, and my son loves it more. There are a couple of spots marbles willrarelyget stuck, but in something this complex I think that's practically unavoidable. I'll likely buy other similar sets in the future.

Asked for this at Christmas (just for something different) and got it. As someone who has 50 years experience building scale models, this was easy for me, but I would not recommend it for someone who has never built anything like this before, and kids will need adult supervision when building it.Aside from what's included in the kit, I'd also recommend that you have a sharp hobby knife, a good pair of tweezers (some parts are very small), and either fast-setting wood glue or a superglue that also works on wood.The main difficulty for me during the build - other than not getting fingerprints on the clear acrylic parts - were the clear plastic axle washers / spacers... clear plastic isn't very flexible, so I would defintely recommend using wax (included) on the axle pieces to put those washers in place; you will still need some muscle to get those in place.Breakages can be easy if you're not careful - this is just thin plywood for some parts. For any parts that push into the base, I'd suggest opening the holes in the base just slightly, otherwise you'll be putting a lot of pressure on a fragile part for a very tight fit. And yes, to repeat, be careful - these parts are fairly fragile just because they're thin plywood. Some parts should be carefully cut out of the sheets instead of just pushing them, and you should definitely trim / sand the parts where they were connected to the sheet.Following the instructions, the build was easy enough, and they do include QR codes in a few steps so you can see where a part goes or where it fits. The only exception - as far as doing the steps in order - would be the nameplate with its sticker (one of the last steps)... I'd suggest doing that as one of the first things before you build anything on the base, so you have easy access to the brass screws for it. Also make sure that you trim any excess from between the various sections of the spiral... follow the markings.Overall, the build was fun and easy - two (long) afternoons; I'd say that overall, assembly will take 10 hours or more. The operating machine... not bad, could be better. Make sure that you 'grease' wood pieces that rub against each other (especially the gears) with the wax included. The wedge that pushes the balls out of the acrylic gear and on to the track needs reinforcement, so crank slowly; otherwise a ball might not get pushed out, and could end up following the acrylic gear around, dropping to the ground.I would recommend this for someone who likes to build, but not necessarily as a toy that will get used often. Though you must admit that it makes a good conversation piece.