For the customization of ferrules, the possibilities are endless. From color to material, you can choose anything you like based on the brush design & function. Also, you can mark your logo on the ferrules.
Most ferrules are made of steel, including tin plated steel, stainless steel , copper plated, brass plated, etc.. Some times, plastic ferrule is also selected option, sepcially for round head brush
The color in the left photo is the most commonly selected.
Glossy, matt, & brushed finish