We made a guitar with a shoe box and rubber bands.
We made a tambourine by tapping 2 paper plates together with popcorn kernels in the center. (It was a lot like a rattle and my little girl loved it!) You could also attach bells to the outside of the plate for a different sound.
My little guy wanted a big one so we used the center from wrapping paper and stuck tons of toothpicks through it. (You could also use a paper towel center or toilet paper center)
This looked more like a weapon to me then a musical instrument :) We ended up cutting the toothpicks down and wrapping the tub with tape.
This is what the inside looked like.
We then filled it with popcorn kernels and tapped the edges closed.
We also had fun with drums! We just used a bunch of empty containers I had saved.
We also had lots of fun just singing songs and finding things around the house that made noise. My little boy loved making the sound of horse hoofs by clapping two bowels together...my little girl loved simply clapping! Our favorite was turning the radio on and dancing...both my little guy and girl loved spinning and I loved watching their fun moves!