stˈʌd fˈaɪndɚz hɐvbɪn ɪn jˈuːs sˈɪns ðɪ ˈɜːli twˈɛntiəθ sˈɛntʃɚɹi, ænd ðə fˈɜːst wˈʌnz wɜːɹ ˈɔːl mæɡnˈɛɾɪk, ɹᵻlˈaɪɪŋ ˌɔn ɪntˈɜːnəl mˈæɡnɪts tə dɪtˈɛkt ðə wˈɔːlɪŋ fˈæsənɚz ɔːɹ nˈeɪlz pɹɪzˈuːməbli ɐtˈætʃt tə stˈʌdz.
Stud finders have been in use since the early 20th century, and the first ones were all magnetic, relying on internal magnets to detect the walling fasteners or nails presumably attached to studs.