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, like gardening tools and cleaning tools and some uncommon hammers.