This video looks like it would be a fun project:
I built a catapult and ballista for my daughter’s science fair. It wasn’t with the Maslow though. 

I’ve built several trebuchets at the boyscouts, but they were pretty wobbly 
They have some fun science behind them, but pretty much require solid wood which isn’t what the maslow is best at.
the maslow can do solid wood, but watch the first video, he’s using a CNC to cut
the brackets to hold 2x4s together.
You can see this:
http://www.tasigh.org/ingenium/medium.html
http://www.woodworkersworkshop.com/resources/index.php?search=trebuchet+plans
Anf finally the shopbot web page:
http://www.shopbottools.com/mSupport/projects.htm
TrebuchetSheet2.dxf (356.9 KB)
TrebuchetSheet1.dxf (420.9 KB)
Trebuchet-.pdf (1.4 MB)
I need the help for my 6th grade project.
what sort of help?
David Lang