nerf shooter

This is what has kept my boys interested for hours. Saturday they pulled out our old marshmallow guns and played with them for awhile. before long they started taking them apart and combining parts until.... drum roll please, they got the ultimate nerf shooter. to compare look at their statistics;

• It shot a nerf dart 124 feet and 2 inches.
  
• The normal (purchased) gun shot the dart 26 feet.
• A marshmallow only goes 58 feet

It hits the wall with a satisfying thud. Unfortunately it hit the ceiling fan chain with an intriguing zingy zapand the chain is wrapped around the light fixture!

I'm through doing anything downstairs since the air conditioning is not working here. We have a fried circuit board but it should be fixed by tonight. I'll spend the day upstairs trying to clean up and getting started on a project. The only problem is which one?