My 10 years old enjoyed a long moment working on this. The mechanisms are very impressive. A few pieces were lost in the process (or missing?), filled the form on the website and had a very good service, received in one week. My son found it quite interesting but challenging, there was a few cases where it would jam because he cannot execute everything perfectly. One time it was an execution error (backtracked and found himself, good learning), other cases was a small detail (eg attaching pins not fully removed), and finally some cases where we couldn’t fully find the cause (something would create some resistance). The resulting arm works, but the opening/closing of the grippers works only sometimes, something is not running smoothly. All in all, despite the challenges, he enjoyed, and we ordered the wired control robot arm, which should be simpler, and will be interesting to compare both.