Carol DuBosch designed this simple and inexpensive penholder, which is also called a DipStik. The ingenious design consists of a wooden dowel with a small piece of plastic tubing. The tubing holds the nib snug and provides a nice cushion for your fingers.
To remove the nib, pull the plastic tubing off the dowel (the holders are inexpensive enough, though, that you can have a separate holder for each nib, leaving the nibs in the holders). 5.75 inches.