To hollow out wax patterns it is best to judge thickness of wax by holding up to a light and judging the color of the wax. The deeper the color the thicker the wax. The lighter the color the thinner the wax. To assist you while carving buy a light box from an art supply store or crafts store. These are used for tracing drawings. By holding the wax on this you can judge the thickness of the wax while you are carving. (It also comes in handy when making sketches for customers)
An alternative to the light box is to use a small florescent light fixture made to mount under a shelf. Lay the light on your workbench with the light shining up and use the diffuser as your work surface. To cut down on the glare from the light cover the diffuser with a shop towel leaving an opening for your work area.
How to training videos for Bench Jewelers
See some of the most respected Master Jewelers explain their techniques and tips
on stonesetting, making and repairing jewelry.