I bought this for my grandson.  He loves Legos and building and we had great fun building these machines.  It was a great exercise in following directions and building step-by-step.   We did not complete all the machine in this book before I gave him another one in the series.  Several of these have not been used.  ALL Lego pieces, balls, and string are in the set!  I think all the paper pieces are in the set now, but I am not certain.