Pretty simple to build. I would suggest when notching the main body and the front piece, to notch the main body only about 1/2 an inch and the front about 3 1/2 inches. The body is very thin, so having it notched all the way down can, and did, cause it to break. Just a suggestion though.
Also the plan does not include the braces for the body to attach to the rocking legs. I just measured the base of the scooter wheels and added about 1/2 inch. I cut that width off the end of the remaining wood.