I've always though that about tinkering as in "being in love to work with inner working of things and understanding the internals, mastering stuff". Nothing pejorative.
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.
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.