A favourite of many people is sanding with the grain of the wood; some will happily sand for hours. Collections of tree roots and limbs or drift wood can be an inexpensive resource.
Sanding with the grain of the wood is where the idea for surface appearances got started. Below ACL 5.2, people simply do not understand what will happen when you put stain on after sanding against the grain of the wood. The surprise comes when they still do not understand after the connection is demonstrated to them.