tinker

a person who enjoys fixing and experimenting with machines and their parts

formerly a person (traditionally a Gypsy) who traveled from place to place mending pots and kettles and other metal utensils as a way to earn a living

small mackerel found nearly worldwide

do random, unplanned work or activities or spend time idly; "The old lady is usually mucking about in her little house"

work as a tinker or tinkerer

try to fix or mend; "Can you tinker with the T.V. set--it's not working right"; "She always fiddles with her van on the weekend"