Here's the details for making the very simple cake tray I used for one of my April By The Cute And Girly projects.
Take a piece of 12x12 cardstock, double sided patterned is nice or just a piece with block colour on both sides would work. I've used white on the example so that the marks show clearly.
Cut away 3 inches from one edge (save this to use for a handle, I halved mine so that it was 1.5x12 inches).
Score 2 inches in from each side of the remaining card. Score the squares in the corners diagonally, (I've drawn the line on the picture below to make it clear).Fold up all of the four sides with the diagonal corners pointing outwards, to make an 8x5 inch box. I used double sided tape inside the little triangle corners to hold the box together and then added holes for ribbons later.
That's it, leave a comment or e-mail me if anything doesn't make sense and I'll get back to you.
** Kate **