It’s probably also worth mentioning the downloadable guided meditation audios that go with Analayo’s Compassion & Emptiness book:
The first two focus on the Brahmaviharas, 40 minutes each, the first focusing on the four divine abodes, with the second combining these with practice of the seven enlightenment factors.
The following is a link to several Analayo meditation audios (various types of practice, not just metta):
There is also Ajahn Mahachatchai’s method of Metta, which Bhante Sujato practices. Check out the post here for a link to a YouTube series describing this method. Or see the book, A Flower Called Metta, here: