I apologise because this is a more complex way of doing a cover, hopefully you can figure out how I do it with just one fabric/colour. I came up with the design of a red stripe about 1/3 the way up. Figured out all the maths and cut a piece of buckram the right size.
This photo is just a check, I was happy with the size of it.
The next step is to flip it over and align it properly (there are marks where it should be)
I put my weight on the back cover
Lift up the left, and mark the segments for gluing and do the same for the other side.
Because gluing is stressful and quick I didn't have time to snap all the pictures I wanted. Basically what you do is: With the left cover lifted, glue the buckram on the left and the middle then push the left cover down. Move the weight onto the left cover and lift up the right, gluing the buckram underneath. Flip the cover over and with your bonefolder go in and make sure the buckram is sinking right down into the spine and there is no air bubbles anywhere. Sometimes the edges aren't stuck down very well and a little more glue requires adding.
Tip of the day: Just use the width of the rule to chop off the excess and neaten the edges before you fold them over.
Make sure it's stuck to the edge of the cover, give it a solid rubbing down with your bonefolder. When your happy, then push it down and rub the top down.
Ok so I do the same for the black.
Another tip, for the corners get your set square and line it up 5mm from the end and then just cut down the angle. You can then glue and fold.
ALWAYS FOLD THE SIDES FIRST AND THE HEAD/TAIL FLAPS SECOND
Note: When working with more than one fabric I usually overlap the fabrics by a couple of millimetres to stop dust and peeling.