ephod: See study note on Judges 8:27.
household idols: Compare Genesis 31:19–32; 2 Kings 23:24; Zechariah 10:2. The Bible criticizes the powerlessness of these personal gods. Micah making his son his personal priest was very unusual: The father was supposed to lead the family's religious activities (Deuteronomy 6:7; Job 1:5), only Aaron's descendants could be priests (Exodus 28:1–29:37; 30:30–33; 40:12–15), and priests served all of Israel, not just one family.