Watches

Dozens of parts in one movement, and you notice every second it gains or loses

You don't need an expensive watch to begin: an affordable mechanical piece teaches automatic winding, daily accuracy and service intervals. People soon split into collectors of brands and models and tinkerers who regulate, service and swap parts with a set of screwdrivers and a loupe. The secondhand market is full of refurbished and frankenwatches, so learn to read a movement before spending big.