Acetone
Acetone is a useful solvent for the plastics industry. Furthermore it has many general purpose uses, and is quite safe to humans - it is not dangerous unless exposed to fire or ingested. Small amounts of Acetone evaporate when exposed to air.
Safety
Acetone is flammable. It is not corrosive, and does little more than dry human skin (though keep away from open wounds).
How to Use Acetone
Cleaning Tools
Acetone can be used to clean off many kinds of uncured and cured plastics and polymers from tools. Tools can be soaked in an acetone bath over time. It is best to cover any open containers of Acetone, as it both evaporates, and is flammable.
Preparing Surfaces
In cleaning a concrete floor, for example, Acetone can be used as an alternative to water as it will evaporate quicker. This is done when preparing a concrete floor for finishing (epoxy, urethane, etc).
Cleaning Hands
Acetone can be used to clean resins off of hands or surfaces. Simply apply, and rub the acetone in.