Most of my customers use their rods heavily, and many are tournament fishermen. Their decisions to utilize traditional materials with limited customization stems from the knowledge that these rods will be banged around, bumped, thumped and generally used and abused over the course of their service life. The extra costs associated with customization just aren't worth it when they beat the heck out of their equipment. Add the fact that decorative handles don't help them catch any more fish, and I think that you can understand their decisions to utilize traditional materials and designs. Subsequently I have limited the amount of time that I have dedicated to creating custom handles.
Custom handle design is a very intriguing type of artwork.
If you ever have the chance to see some custom built handles with inlaid metals, variegated coloring and multiple materials you'll understand why I consider them art. It is probably the most comprehensive collection of information on techniques and ideas available anywhere. Specie cork is the type used in most handle construction. You can recognize specie cork by the alignment of the pits in the cork. The pits in specie cork are aligned parallel to the hole in the ring.