Expolding Boxes

Hi I am new to this site, this is only my 2nd post, can anyone help me with the dimensions to do an exploding box from A4 card stock instead of 12" x 12".

Thanks in advance
Happy crafting all

the measurements for a A4 exploding box -
outer layer: cut card to 21cm sq. mark at 7cm all round
middle layer: cut card to 19.5cm sq. and mark 6.5cm all round
inner layer: cut card 18cm sq. and mark at 6cm all round
lid: cut card 13.5cm sq. and mark at 3cm all round.

Found this question on docrafts and this was the answer. Was that you????

A much better explanation than mine but I thought you might like to view some pictures of how to make.

http://glitteradventure.blogspot.com/2006/11/exploding-box-class.html

Janis x