I’ve done a bathroom mirror by gluing shells around the border.
Jeri, here are a bunch of ideas for you. I buy the cheapo 1'x5' mirrors at Walmart that have the thin plastic frames. Take the frame off and you have a great piece of mirror to work with!
You can use any baseboard you like from the hardware store as a frame. You’ll also need a thin piece of particle board for the back.
I framed my big old bath mirror with strips of sticky backsided fake backsplash paper. cost - $1.00