If you prefer a long-lasting battery with a base attachment, Ryobi makes that too. The 12V cordless rotary tool and the 18V rotary tool (with the base) are available for $61.50 and $84 ...

It's great for cutting wood, drywall, PVC, trim, and even metal,–particularly when the piece you want to cut is in a tight or awkward location where larger rotary and circular saws won't fit.