I've been in business making products for almost 18 years, and I <i>still</i> have problems estimating how long it will take to complete a custom job for a client.<p>Whenever I am asked to bid on a project, I try to remember the "3X" rule: estimate the amount of time it will take, then multiply by 3. This usually turns out to be a good estimate of how long a project will <i>really</i> take.