Tinkering is more or less synonymous with dabbling, which is used more these days. Synonyms with tinkerer would be amateur, hobbiest, dabbler. There’s definitely an implied interest in how things work, but also strongly implies that one is not serious about what they’re doing.

More in line with your definition would be artisan or craftsman; although fwiw craftsman can have a negative slant in modern (American) English as some people use it in lieu of blue-collar workers.