The Paint Brush is a tool used in the RedPower mod that lets you colour Pneumatic Tubes. Items passing through Pneumatic Tubes that are tagged with a colour (e.g. by the Sorting Machine) will not pass through tubes of a different colour. Furthermore, coloured tubes of different colours will not connect to one another. Unpainted tubes, however can join to any colour of tube. Tubes lose their painted colour when broken.
A Paint Can is used to add color.
NOTE: Any color of Wool is allowed; the output will always be an 'empty' paint brush, however.