This kit is simple to assemble. The instructions were fairly easy to follow with decent illustrations. There are some very small parts, plastic tube used as retainers for the axle shafts. They aren't difficult to get on, just easy to drop and lose. I'm sure they would send you more, or you could find some 2mm hose to make them. The engine has a heavy base so it is quite stable, the parts are nicely cast. There are no glass parts to break, it's all metal so it's not fragile. I lubricated the pistons with a bit of graphite, the main shaft has ball bearings. It starts quickly and runs fast. This is a good kit for anyone who is interested in engines.
This was absolutely as advertised. In assembling the kit, which took about a half hour, I learned a lot about the engine.
This is very basic designed desk gadget for education in technical sciences. Any one watching is fascinated by the working principle. All parts are explained how to be assembled. It is fun putting all the parts together and even more fun to see the working principle of a vacuüm engine. What is especially appealing to this design is that there are no redundant parts or shapes.
Collected with the child, everything works fine, turns for a long time. The main thing is not to pull the connections, leave gaps, so that the details rotate freely.