My 4-year old and I have been working on this ottoman for about a month.
I am not kidding.
We only do it when the littler guy is sleeping, and not every time. Our first step was to take a piece of plywood and cut six equal pieces out of it. We labeled them for which side they would become. Then we screwed the sides and bottom together using the drill. Then we found a hinge and put it on the top piece.
Then we cut foam for the top and bottom, and fleece. Then we handstitched the top (I did the edges and he did the decorative stitches). Then we stitched the sides, then the inside.
Lastly, he decorated it with stickers and we hot glue gunned a piece of leather on one side and a piece of fleece that had been covered in tape (to act as casters and help it slide) onto the bottom.