Step one: bake four coloured cakes or two vanilla, two chocolate. An 8" square tin needs a four egg cake to make an inch and a half high cake. You need 5 of these to make a cube.
Cut them to the same size with a bread knife.
Use a tape measure or ruler and cocktail sticks to mark out 1" squares.
Cut out and separate the rings.
Use chocolate ganache or white icing to stick the smallest square.
Spread icing around the outside of the cube. Add the next ring.
Repeat for the whole layer.
Make each layer on the same manner alternating colours
Cover in white icing and decorate.
I made coloured roll out icing the previous day to stick on. This was quite brittle so probably best to only leave it a few hours.
You rip what you sew!