What do I use to Frame a bathroom mirror?
Crown moulding works great.
Here is a great tutorial: https://www.momtastic.com/diy/128900-how-to-frame-a-bathroom-mirror/#/slide/1
Great idea from Fiddledd, crown molding also comes in Styrofoam-which make it light weight and paintable. Visit your local DIY store to see what they have or look online at Amazon.
Depends on the look your going for. If it is country you can get some used 1 x 4 (maybe from a pallet or old building) cut them to size and depending on the type of corners you want, put them together to form the frame then attach over the mirror.
If you going for a more elegant or formal look buy some molding from a home improvement store. Measure the overall length of the mirror and leave yourself a little extra room because when you miter the corners you will lose some length.
Also take into consideration how much you want as an overlay on your mirror. 1/4" is about what a picture frame is. Which brings to front that a picture frame the right size would work too.
Depending on the style and weight of the frame you will need to put anchors in the wall to screw in and hold the frame.
Wow that was fast. Thank you, I will look into all of the suggestions. 😍