Hi everyone!  So i have a 90th birthday cake due.  I am going to be making a memory box of sorts and fill it with memories from his life.  I have made a present cake before, but never a box with stuff sitting IN it. 

Does anyone have any tips or instructions on how to make a box with stuff sitting IN it.  You know, so that there is that 1 inch or so lip so that it looks like it's actually sitting inside the box and not just on top of it??

Thanks so very much!!