The barrel is the first thing that strikes your eye. The color, texture, and the way the light strikes the material. The barrel sets the tone for the entire aesthetic experience of the pen.
The material also determines how light or heavy a pen will be and what it feels like in your hand. Need a heavy pen? Then brass is what you need. Brass gives the pen weight. Need a light pen? Then acrylic is the best choice.
The common types of materials used for fountain pens for mass manufacture are chrome, brass, and acrylic. Custom made pens have used material such as wood, bone, and antler. If you choose to have a custom design creator to make your fountain pen such as desert pen turning uses wood, bone, antler, acrylic, brass, and chrome. You can have various color combinations, intriguing patterns, carve or burn a unique design into the surface of the barrel this will help make the pen unique and maybe more valuable.