I have modified the "magazine rack" card holder I created earlier this year to make it more sturdy and to ease the process of putting it together. It requires a 12 x 12 piece of cardstock and holds A2 sized cards with envelopes. You mark and score the lines, make a few cuts and fold it on all the lines. A few pieces of double sided tape in the right spots and it comes together quite easily. I just decorated it with a piece of decorative paper and added a book plate but you could decorate it with whatever your little heart desires!!
These are great for putting on your book shelf to hold any extra cards you have made for future occasions. They could also store any cards you have kept to provide inspiration!! Might also be a wonderful way to package cards for gift giving!!