Jamieson, Fausset and Brown on Judges 17:5

5. the man Micah had an house of gods--Hebrew, "a house of God"--a domestic chapel, a private religious establishment of his own.

an ephod--(see on Ex 28:6).

teraphim--tutelary gods of the household (see Ge 31:19 and see on Ge 31:26).

consecrated one of his sons who became his priest--The assumption of the priestly office by any one out of the family of Aaron was a direct violation of the divine law (Nu 3:10; 16:17; De 21:5; He 5:4).