Graph Paper is great to use for the pattern. It is pretty basic. Make sure the outside walls are 3.6 or 3.7 inches tall to hold the ATCs. I staple the second inside wall to the outside walls on the edges to form the pockets. you can add a third inside pocket but make sure it is big enough to hold ATCs. I just made a grassy area and stacked a bunch of ATCs on it and put my self portrait doll with them.
The lid will need to be glued together where I have indicated tabs. i suggest that you cover all the pieces first to chipboard on both sides before you even begin to assemble them. Also the dotted score lines will be useful. Be careful not to cut through though. I used my own hand painted paper and inked the edges.
ROOF- I cut out four long elf hat shaped pieces for the roof and connected them together in the middle and curled them and embellished them.
This is so fun to make. Check out the Brownie and Fairy House boxes as well in the other posts below. They are fun as well and can still be used for more ATC houses instead of picture if you would like.