The things I mention here as toys for preschoolers are clearly not all "toys." Please use your discretion when looking for things for the mechanically-minded toddler and/or preschooler!!
Also, I'm providing random links for stuff as I find them. If there is a specific toy/brand that I've liked then I use it. Otherwise I provide a link just for the sake of description. For example, in this day and age who knows what I mean by "rotary egg beater?"