Here's my approach.
If you're still giving this a try, don't look at the answer below.
If you're ready to see it, open the attached SKP file and follow along.
Working from left to right,
1. I drew a box representing the size of the blank from which the X would be cut. I selected the front face and its bounding edges (double click on it) and copied it straight out in front of the box. The distance is not critical.
2. I drew the curves on the side of the box for the final curved shape of the X. The original plan gives the height of the back arc and the final thickness of the piece so I drew the back arc and used Offset to get the front arc. Guidelines were placed to aid in drawing the bevels at the top and bottom of the blank.
3. Push/Pull took care of the curved blank. A couple of guidelines assisted with the placement of a 2 degree Bezier curve on the face out front. I drew the left edge curve and then used offset to make the larger curve since I knew howwide the legs of the X are to be. I selected the curves and copied them to the side.
4. With both curves selected, I copied them along the red direction and then moved them into place to make the corresponding parts of the X. When Moving the curves back into place grab the outer one at its end and move over to the corner of the face.
5. Select all of the single face and the curves and run Intersect. Next delete the unneeded stuff leaving the X profile.
6. Push the x profile through the curved blank.
7. Select all of the resulting geometry and run Intersect. Then delete the waste.
8. Select all of the geometry and rotate it backto the correct angle. In this case that's 8°. To keep the orientation of the Rotate tool correct, Orbit around to the side and down low until you can get the protractor to be red. Hole the Shift key to lock the orientation and then click on the bottom front corner to set the center of rotation.
Although I didn't do it in this example, I would make a component of the geometry prior to rotating it so that I get the smallest possible bounding box which would make getting an accurate result for a cutlist easier. It would also help when applying textures.
X slat tut.skp
Inspecting mirrors is a job I could easily see myself doing.