I printed this little train set for my 18-month-old grandson. His eyes lit up when I gave him the engine, and he insisted on taking it for his nap. I gave him the set, and he spent more than an hour exploring how they connect. His father wants one for the house that he swears he won't play with.

While I praise most of the design for its simplicity, the wheel and axle set does not work well. Even printed at 100% infill, the wheels break off too easily. I checked the comments on the original train, and noted that I wasn't the only one needing a safer alternative. I've never used TinkerCad before, so it was a challenge, but I managed to make a round and centered wheel.

I print these with a concentric pattern, at 100% infill. They'll take about 20 minutes apiece. You will need a 33mm section of 3/16" wooden dowel for each wheel pair. If you use clippers, make sure you re-round the ends. I made the hole a snug fit, and you may need a bench press to put them together evenly. If you feel the need to add glue, I would recommend E6000 or similar craft glue, because it stands up well to vibration. Little ones do love to smack their toys around.

I recommend having a track section handy so you don't press the wheels together too closely.