Material
Wood dowel
A straight round rod can be a handle, axle, spacer, or part of a frame.
Get to know it
Roll a dowel on a flat surface to look for bends. Its diameter and stiffness must suit the job: an axle needs clearance in its bearing, while a fixed handle needs a secure joint. A loose fit and a tight fit solve different problems.
Mark and cut the length for the actual assembly. Round or sand the ends. Do not bend a wooden rod into a crank; attach a separate crank arm or disc instead.