2 Corinthians 3:18 But we all, with unveiled (the veil is the flesh) face beholding as in a mirror (those who have been created in the image of God) the glory of the Lord, are transfigured into the same image from glory to glory, even as by the Spirit of the Lord.

And all of us, with unveiled faces, reflecting like bright mirrors the glory of the Lord, are being transformed into the same likeness, from one degree of radiant holiness to another, even as derived from the Lord the Spirit.  Weymouth New Testament

2 Corinthians 3:18 But we all, with open face beholding as in a glass the glory of the Lord, are changed into the same image from glory to glory, even as by the Spirit of the Lord.

The word, "open," is "anakalupto."  Anakalupto is related to the word, apocalypse, and it means a taking away of a veil.

When this verse speaks of being changed, the word in Greek is "metamorphoo"  Metamorphoo is the word from which we get metamorphisis.

Metamorphoo is only used in a few verses in the Bible.

Matthew 17:2 and Mark 9:2 both refer to the transfiguration.  So 1 Corninthians 3:18 could well be read this way:

Romans 12:2 is the other verse where metamorphoo is used.

Note that this transfiguration, in both cases where it is applied to us, is something that happens to us.  It is not something we can do.  It is in the passive voice in both cases.