3 So when he had returned the eleven hundred shekels of silver to his mother, his mother said, "I had wholly dedicated the silver from my hand to the Lord for my son, to make a carved image and a molded image; now therefore, I will return it to you." 4 Thus he returned the silver to his mother. Then his mother took two hundred shekels of silver and gave them to the silversmith, and he made it into a carved image and a molded image; and they were in the house of Micah. 5 The man Micah had a shrine, and made an ephod and household idols; and he consecrated one of his sons, who became his priest.
Matthew Henry's Commentary on Judges 17:3-5
Commentary on Judges 17:1-6
(Read Judges 17:1-6)
What is related in this, and the rest of the chapters to the end of this book, was done soon after the death of Joshua: see Judges 20:28. That it might appear how happy the nation was under the Judges, here is showed how unhappy they were when there was no Judge. The love of money made Micah so undutiful to his mother as to rob her, and made her so unkind to her son, as to curse him. Outward losses drive good people to their prayers, but bad people to their curses. This woman's silver was her god, before it was made into a graven or a molten image. Micah and his mother agreed to turn their money into a god, and set up idol worship in their family. See the cause of this corruption. Every man did that which was right in his own eyes, and then they soon did that which was evil in the sight of the Lord.