QMK Italian accents
See this keymap, in particular:
[_ACCENT] = LAYOUT_planck_2x2u(
_______, IT_EURO, IT_AT, IT_EACC, _______, _______, _______, IT_UACC, IT_IACC, IT_OACC, _______, _______, \
_______, IT_AACC, _______, _______, _______, _______, _______, _______, _______, _______, _______, _______, \
KC_LSFT, _______, _______, _______, _______, _______, _______, _______, IT_SCLN, IT_COLN, _______, _______, \
_______, _______, _______, _______, _______, _______, _______, _______, _______, _______ \
),