Last winter I made about 30 of those never stained, painted, varnished any of them. Balsa wood no splinters baby friendly you can eat it for ruffage. Sold them all at 10 bucks a pop. Once set up could make a car in about 15 min.
Good toys that kids love. Wood is much better than plastic and you know how kids are the first thing they do is stick them in there mouth and chew on them.