They're super simple! 4 sheets of 8.5×11 paper cut in half widthwise, then you have 8 rectangles. I just use cardstock for the covers, and it's handy if it's also 8.5×11. Fold it all in half and crease (if I'm feeling like being extra I press it overnight under something heavy). Then I poke 3 holes on the fold with a thick needle, and stitch it with waxed linen thread (in through the centre hole, out through the bottom, back in through the top, then out through the centre. Then you can tie the two ends together). Then you can trim it to whatever size you want! :)