From the outside, a cover made with a version of today’s card case looks just like the one I showed yesterday. (The orange-y book is yesterday’s fold, the flowery one is made with today’s version.)
This picture of the inner covers shows the difference.
To make a card case using today’s fold, start with a sheet of paper with the long measurement placed vertically. My paper was 8.5 x 11″, but A4 will work as well. Score a vertical line 1.75″ (4.5 cm) in from each side. Fold the sides in, then open flat and turn in the lower corners.
Fold the sides in again. Rotate your paper 180° and turn over. Score a horizontal line 3.75″ (9.75 cm) up from the bottom edge, then fold the bottom edge up along that line.
Using the upper edge of your folded section as a guide, score another horizontal line and then fold the top section down.
Tuck the bottom section inside the top, fold in half vertically, then rotate 180° again. Done!
If you have a shorter piece of paper, you can still make this case. The important thing to remember is that your paper must be long enough so that you can at least fold up the portion with the turned-in corners.
The layout below is not to any particular scale, but was drawn to help explain the measurements you need to keep in mind when scaling the fold for the card case so that it can be used as a book cover.
The width of column A is the width of the folded edge section, the width of column B is the width of your book block plus whatever fore-edge overhang you want, and the width of column C is the width of your spine plus enough ease to allow the cover to close properly. The distance from the top edge to horizontal line 1 is the height of your book plus whatever overhang you want at the head and foot. The distance between line 1 and line 2 is the same. The distance from line 2 to the bottom is variable, and will determine the height of the pockets with the folded back corners.
We are approaching the end of the Advent posts for 2018, so there are only two more book covers to show you. Tomorrow’s cover will be an adaptation of one of the interlocked structures I came up with earlier this year while playing with bits of paper.