After School Engineering Club

This year I am starting an after school engineering club that will meet each week.  Over the past few weeks I have researched a variety of curriculum to use for our club meetings.  I really like the Engineering is Elementary and the Time to Invent curriculum.   The Engineering is Elementary curriculum is quite expensive, but explores a variety of engineering fields.  The Time to Invent curriculum is free, but you do have to purchase supplies.  Have any of you ever conducted an engineering club?  If so, I would love some feedback on how you ran your program.  For the rest of you who might also be interested in this after school club, here is the free teacher's guide to the Time to Invent program:   http://timetoinvent.org/activities/  I hope to hear from some of you!!