Step 3: Measuring and cutting the tablet bezel

Take the LCD out of the lid and place it to one side. In fact, place everything except for the lid and the thin plastic bezel you forced off earlier aside. This step is going to get messy!

Place the bezel on the lid, as it was before you removed it during the teardown. With the bezel held firmly in place with a bit of masking tape, use a pencil and draw on the inside of the bezel onto the lid. Make sure your pencil is vertical, otherwise your bezel will be lopsided! Once you have drawn a rectangle on the inside of the lid, and you are satisfied it is good enough, you can remove the bezel and place it to one side.

Take the lid to a garage or workshop, or somewhere where you can make plenty of mess. We're going to cut the aperture for our screen! 
Mask the shiny side of the lid as shown in the photo. This will provide a cleaner, non-shattered cut, and will protect the surface of our new bezel. Flip the lid over, and lay it on some sacrificial plywood or pine. Use a small sacrificial piece and a clamp to stop the lid from moving around when we cut it. 

I drilled holes in the corners for a nice fillet. I then cut the aperture using an oscillating saw, and I thoroughly recommend this method if you have one. It doesn't produce a lot of waste, easy to follow the line, and its easy to manipulate. It's also by far the safest saw to use. However, this can just as easily be done by drilling a hole and using a jigsaw, or a hacksaw/padsaw.
Always cut on the inside of the line, and rotate the lid so that you're always cutting near to the clamp (reduces vibration). 

Once you've cut the aperture, you'll need to run a file or knife around the inside and outside to remove the burrs. On the outside, do this carefully to avoid chipping the gloss finish. Whilst you're making a mess, you need to grind off the Inverter Board plastic housing and there is a slight edge on the bottom part of the lid that needs to be filed off too. Then your new bezel-lid will fit flush onto your base!

Test the bezel with the screen to see if it fits, and then you can file and smooth down the edges.

Or, for those with a Router...

The only problem with cutting the bezel, is that you get a sharp right-angled edge which would be uncomfortable to lean on. When I fitted my bezel to the screen, it obscured part of it. With these thoughts in mind, I decided to chamfer the edge, to make the tablet easier to work on once finished.

To begin, I made a jig out of plywood strips nailed to chipboard. The plywood has to be tall enough for the bearing of the bit to follow. The plywood rectangle was measured to the screen size and the bezel was fitted to this with double-sided tape. 
Trying to get the router to follow this guide alone would have produced a wobbly edge, and so I made some plywood outriggers, and packed them up with cardboard. Now my router could follow the guide without tipping over!
I made the first cut with a 1/2" flush bit with bearing guide, and followed it with a depth-stopped 1/4" chamfer bit with bearing guide.