Tecno Jumbo

My 4-year-old can snap the perforated plates together into a little cart without me helping at all, which is a first. The plastic has survived being stepped on more than once, so it's tougher than it looks.

The bolts actually hold tight once you twist the wingnuts down, so the little cars he builds don't fall apart mid-play. No tools needed either, which means I'm not constantly called over to help. Plastic feels sturdy enough to survive being stepped on, which says a lot in our house.

My 4-year-old can snap the perforated plates together by himself, no help needed, and the plastic has survived being stepped on twice already. The wingnuts are chunky enough for small fingers to grip, which was my main worry before buying.