I used Carson Nicely's video https://youtu.be/bWCVy5lk8BY as a reference.
Step 1: First Start by Taping the Mirror
I taped the mirror off 1.5 inch all around the mirror, you want to make sure you have enough room for the frame.
Step 2: First Step to Sanding the Mirror
I laid the mirror on a towel, make sure you wear a mask and keep it wet so you don't breath the dust in. Some mirrors can contain lead. For the guide on the dremel I used was a top of a pop bottle and I put a hole through the lid and screwed the nut back on. when sanding I used a cup of water and a towel so I could put water on it and wipe it down. I sanded close to the tape but not on it.
Step 3: Second Step to Sanding the Mirror
I lightly clamped down a metal ruler and put it on the edge of the tape to get a remove the final bit of coating in a clean line. Don't forget to water down the glass a bit.
Frosting the glass--I didn't show the next step but I used both a diamond coated bit to etch the glass and liquid etch too. If you don't want to do that you can buy a frosting spray for glass.
Step 4: Start With Your Frame
I found some trim at our local scrap store, mine was 1/2 inch x 1 inch, but really that part is to your preference. I used a miter box for the 45 degree corners, I glued with Gorilla glue and clamped together and the corners were done with finishing screws.
Step 5: Wight Out
I cut the backer board to the sides of the frame and used flat white spray paint on the backer board and the inside of the frame for light reflection.
Step 6: LED Lights
I bought ribbon LED lights with adhesive, you have to leave room for the frame. I realized after I put it together I should have made little bit more for the frame. I measured the length of the LED before I taped them to make sure they were even all the way around. When that was done I soldered them together to have one continuous ribbon.
Step 7: Finish
To finish I put the back on the frame and pre-drilled holes for the screws put the screws in, I bought a dimer switch for the LEDs. I put a hook on the back to hang it on the wall but my wife says the ultimate would be to find a small tv wall mount that comes out of the wall to have different angles and to get up close.