Abstract: An assembly of a paint container, a sliding mixing gauge having graduations to indicate the quantities of ingredients to make a paint composition used for spray painting of vehicles and a slidable fastener for securing the gauge in the container and stabilizing its position when paint and other ingredients are poured into the container the mixing gauge being slidable removed from the fastener after measured quantities of ingredients have been added to mix the ingredients and at the end of a paint operation, the fastener is removed from the container and stored in a designated area.