"And Gideon made it into an ephod" (Judges 8:27). Rabbi Shimon ben Lakish said: Three are those of whom "a good old age" is said. Abraham, and it was fulfilled for him; David, and it was fulfilled for him; Gideon, and it was not fulfilled for him, as it is said, "And Gideon made it into an ephod" and it became a snare. And why did he make an ephod? Because Manasseh was not among the stones of the ephod, but only Ephraim, and he had no constellation [no representation]; therefore he made it. And although he made it for the sake of Heaven, it became a snare to all Israel, for they stumbled over it and supposed [it to be a god].
Gideon's Ephod and the Good Old Age He Did Not Reach
Yalkut Shimoni on Nach 64:1
ויעש אותו גדעון לאפוד. ארשב"ל שלשה הם שנאמר בהם בשיבה טובה. אברהם ושוה לו דוד ושוה לו גדעון ולא שוה לו שנאמר ויעש אותו גדעון לאפוד ויהי למכשול, ולמה עשה אפוד לפי (יב) שמנשה לא היה באבני אפוד כי אם אפרים ולא היה לו מזל לפיכך עשאו ואע"פ שעשאו לשם שמים היה למכשול לכל ישראל שכשלו בו וסברו