lightbox
A lightbox helps you create a new drawing based on your last, it's an enhanced method of tracing. A lightbox is needed for drawn animation only
A lightbox is a flat translucent surface with a light behind it and a method for 'registering' your paper, to make sure each sheet is drawn and filmed in the right place.
You can buy one, or you might find some available in your photography department. However making your own lightbox and registration system is fairly simple.
making your own lightbox
Use white translucent perspex, larger than A4, with a cool lamp behind:
There are many ways this design can be improved; but the advantage of this style over any solid 'box' lightbox with sides and a fixed lamp, is these are stackable.
registration
It is essential to keep your paper in exactly the same place when you are tracing and when you are filming. This is called correct 'registration'.
Professional animators use a 'pegbar' and specially punched paper to register their work, however it is fiddly and the holes can tear with over enthusiasm. Relatively accurate registration can be achieved using A4 paper and two flat lengths of wood fixed to perspex at 90 degrees, one for the left hand edge of the paper and one for the bottom edge. (Use double-sided tape to stick down the lengths of wood, then masking tape over to prevent the paper slipping underneath.)
Registration problems can usually be spotted when watching back animation because things that are supposed to be staying still are jiggling around; with wild animation it is difficult to spot registration problems - and it usually matters less anyway!
paper
It is best to use A4 photocopy paper (80gsm) as this is thin enough for seeing through three sheets or more on a lightbox, and is just about strong enough to take paint. It's also readily available when young people start drawing fast....