This is my Kinex set from when I was little. I spent hours building intricate contraptions. My mom kept them for me and now Big Sis is enjoying them. She's still a bit young to make the designs in the book and putting some of the pieces together hurts her fingers (she's kinda a wuss at times, but I do remember as a child having sore fingers after playing with them for too long, so she's got a point on this one). I helped her build the airplane and she's been flying it around the house ever since.