I wrote out a bunch of instructions yesterday just because. Did include screenshot. I hate making screenshots. 😩😩
You must always examine your mesh before you do anything else with it. Remember how I told you it's important to have a clean mesh? Well, it's even more important for CAS items because CAS items have to animate and horrible meshes cause problems with that.
Hint: Press Numpad 5 to enter user ortho view and if you need to zoom into something, select what you want to inspect and press the period key on the Numpad.
There are faces smashed between other faces. At the top of the veil, at the back of the head, you've got...faces on top of faces on top of faces. When you have geometry clipping like that you get flickering in your mesh (Z-fighting). You need to redo the UV map. It's a bunch of random chunks all piled on top of each other. You will have unwanted sharp edges all over your mesh due to this. Better to unwrap entire sections as one big UV island per section.
Unfold the rig and hide all of the body parts. Hide the crown, too. Select the veil, edit mode, press A, W > Remove Doubles. This will remove the extra layers. Don't worry about it; you'll need to redo it anyway. Press T to open the side panel, in Shading/UVs click Recalculate. This will make the normals even. Alt + J to change your tris to quads (fewer edges to deal with, now). In the panel put a checkmark next to Compare UVs. Now your UV map won't be messed up even though you're going to have to redo the UV map, anyway. T to close the panel.
Select a few faces on the inner veil, Ctrl + L, H to hide it. Press P to separate it. Object mode. Select the inner veil and hide it. Now, it won't be in your way.
Examine the outer veil and delete the faces on top of each other and the ones squashed between others. Hide geometry that is in the way (H) and disable limit selection to visible if you have trouble grabbing the smashed faces. Alt + H to unhide and enable limit selection to visible when you're done using it. Look for areas where the vertices should be merged. Vertex-select, shift-select the unmerged vertices, Alt + M > At Center. You might have to disable limit selection to visible to grab the vertices. Again, enable it when you're done.
Press T to open the panel, A to select your mesh, in the shading section, under Faces, click the smooth button to smooth the mesh.
Rotate so you're looking underneath. There are faces around the forehead that are clipping through the top and should be removed—it's an entire layer that doesn't need to be there. Select some faces, Ctrl + L, X > Faces.
There's a little, skinny strip of faces running along the edge of the white edging. It's serving no purpose and is just increasing the polycount. Never include unnecessary geometry in your models that won't be seen; it just makes the polycount higher. I'd remove this if I were you but it will take time because you'll have to merge a ton of vertices. It's up to you just remember to avoid this kind of thing in the future.
You should have just one layer of geometry at this time with no clipping and no smashed faces and all loose vertices merged.
In the UV editor, enable keep UV and edit mode mesh selection in sync. Enter face-select in the UV editor and the 3D window.
Use B and select the islands that will be textured black, U > Unwrap, move the island off the map somewhere. Select the islands that are for the forehead piece. Unwrap, move off the map. With the small strip and the wider edging, use cylinder projection or sphere projection. Move the islands off the map.
Add a solidifier modifier and adjust the thickness as you see fit. Uncheck fill rim. It just adds geometry that won't be seen. Enter object mode and apply the modifier. It will help to go back to edit mode and select and delete any faces that won't be seen. You can Ctrl + L the top layer of the outer veil, hide it, then delete the faces you want via the UV editor. Use B or C to select faces.
Put the outer veil in object mode and hide it then unhide inner veil. Select the inner veil. Edit mode. Examine the mesh and fix any problems you see. UV unwrap as you did before. Add a solidifier modifier, adjust thickness as you see fit, uncheck Fill Rim. Object mode. Apply modifier. You can enter edit mode and delete parts that won't be seen for the inner veil, as well. Object mode when done deleting faces. Unhide outer veil. Shift-select both meshes, Ctrl + J to join them.
Select joined veils, edit mode. In the UV editor, A to select all islands, Alt + O, open the
CAS map. If the islands are stretched vertically, A to select (if not still selected), S, Y, 0.5 to resize the islands. Do this only if the islands become stretched. The veils will now be assigned to the CAS map.
Scale the UV islands down and place them in the hat section of the CAS map. (You can put them in another spot just know that if you put them in, say, the glasses area, but you have the veil in the hats in the catalog, and then you equip the veil and a pair of glasses at the same time the glasses will pick up the veil's texture). Enter object mode.
Unhide the crown. Edit mode. Press A in the UV editor to select all of the UVs, open the CAS map—the CAS map is already in Blender so just click the tiny up and down arrows in the bottom of the UV editor and scroll to the map. If the UV islands become stretched vertically press S, Y, 0.5. Now the crown's UVs have been assigned to the CAS map. Move the islands off the map. Object mode. If you don't join the crown with the veil you'll need to know where the veil's UV islands are so you don't accidentally put the crown's UV on top of them. Shift-select the veil first then the crown second and enter edit mode. The crown should be in edit mode. In the UV editor click View > Draw Other Objects. Now, you'll see an outline of the veil's UVs so you know where to place the crown's UVs. Place the UV islands. Save your file when done.
Aside from this you need to do the weight transfer, uv_1 transfer, vertex paint, and assign the cut numbers. You also need to make the other LODs. Assuming you want the veil to be transparent assign the same cut number as the glasses' lens to the veil.