How much Paint

Buy enough color to do the entire job and intermix the cans before you start to paint anything. It's best to use the same brand base and clear to avoid any compatibility or adhesion problems. Unmixed color will last a long time as will unopened activator. Opened activator has a relatively short shelf life. A few/6 months. I don't take the chance on ending up with a non-catalyzed gummy mess. Urethanes won't dry if the activator is shot.