Rolling Pin Sander
Rolling pin sanders are incredibly useful in lutherie. The biggest problem is that solid drum rollers aren't normally available or the right size of guitars. My rolling pin sanders are specifically made for use on guitars. Since the sander is made to be used with a drill, you also have the benefit of variable speed control. Rolling pin sanders aren't only for sanding sides either. They are very handy in applications like shaping the neck heel profile.
($15 shipping to the continental US, others please inquire)