Create a simple k'nex gun that really shoots.
You will need the pictured k'nex pieces.
Get three yellow half rounds. Put them together with the centre one facing down. Clip a white piece through as pictured.
Connect white piece to back. Add two yellow straight pieces to opposite end.
Attach two long red pieces to outside yellow half rounds and one red piece to swiveling yellow central half round as shown.
Pull red pieces back so you are holding them together. Attach white piece to front as shown.
Pull central red piece forward. Attach blue round to top white piece with large notch on blue piece facing in same direction as yellow straights.
Hold red pieces and squeeze together to fire the blue piece.