Maintenance Man

Maintenance Man is an unmarked quest in Fallout 4.

Detailed walkthrough
After a brief conversation with Calvin, he will buy any tools from the Sole Survivor for 15 caps a piece. The tools he seeks include:
 * Adjustable wrenches
 * Ball-peen hammers
 * Combination wrenches
 * Hammers
 * Screwdrivers
 * Wrenches

Calvin will not buy any other tools from the Sole Survivor, even ones that would seem to make sense, such as hacksaws, surgical equipment, and the rare Claw and Masonry Hammers.