QVC http://www.qvcuk.com have a craft TSV today and lots of craft shows throughout the day - one of the items included die cut exploding box templates and that made me realise that I hadn't put the dimensions of my exploding box up on here yet.
Anyway - here they are:
I marked in 10cm from the edges for the outer layer using the full sheet of card (31cm full width)
For the middle layer I cut the card down to 29cm square and marked in 9 1/2 cm from each side
For the inner layer I cut the card to 27cm square and I marked in 9cm from each side.
The top was made from a square 15 1/2cm with lines scored 2cm from each edge.