Cheap and pretty much useless chisel as frequently offered for sale at fossil shows, the grip being simply too thin to apply adequate force to the matrix with proper guidance to the tip. Preparing the trilobite with such a tool is a safe bet on an unsatisfying result.
Comparably short chisel, home-made by Dieter Holland, constructed from parts used in circuit tester for cars, bearing a flat chisel as a head. Force is applied by the palm of the hand while the fingers' only job is to properly guide the tool.
Another home-made chisel with normal, pointed steel needle. The steel needles used in this tool have to be sharpened frequently.