Thanks. I made it using ABS plastic sheet. First, I cut out a flat bezel shape. I originally tried to use a heat gun to heat it to see if it would conform to the shape of the CRT - it wouldn't. It just wanted to warp. So instead, I made a cardboard template of the curvature and made 4 pieces for the inner bezel which are curved on one side and completely flat on the other. On the curved side, I used MEK (methyl ethyl ketone) to solvent-weld the pieces to the bezel. When all 4 pieces are attached, it makes the bezel curve appropriately. Then I filed and sanded it smooth. I kept all the sanding/filing dust and mixed it with MEK to make an ABS paste with which to fill imperfections and gaps (mostly occurring where I joined the 4 inner pieces to the bezel). Then more filing and sanding. On the backside, I used MEK and more ABS to make the mounting ears so it bolts into where the CRT was.
The ABS I used is leftover from a car stereo project, it's 1/8" textured ABS from Parts Express, but I used the smooth side. Any scrap ABS plastic like from the enclosures of dead/broken electronics would work too, though.