I followed the wallflats link and clicked around, but I can't find the item that resembles molding and is featured in the small, third photo. Where is the picture from, and where can I buy the pro...

Regarding making your own seat out of plywood, padding, and fabric: Don't forget to top it off with a clear, plastic material (sold at JoAnn Fabrics) if the furniture is going to be kept outside. ...