For example, when we pasted the projector,
into the scene, Michael was already there. The
projector covered up Michael's right hand,
which we wanted in front of the projector.

When we pasted the screwdriver into the scene
it covered part of Michael's left hand, which
should actually be holding the screwdriver.

Solution: Always work with copies of original
images. That way if you cover something that
you need, you can go back to the original and
copy just that part of it that you need to fix the
problem. In this case we copied Michael's hands
without any of their backgrounds, and pasted
them into the scene. This put the screwdriver
in his fingers, and the projector behind his hand.