Then I chose my backing fabric and taped the left and right edges to the board. I use double-sided tape for ease and because this is not an heirloom piece, it's for my pleasure now. If you want it to last 100 years, then lace the backs properly.
Next I used tape along the 14cm edges of the side pieces to fix them to the front and back pieces so we have a long jointed piece.
I don't have a photo of the side piece laid out but basically it's a long piece of thin card covered in the same backing fabric. The card is 60cm long allowing for four sides of 14cm plus an overlap. I could have used more wadding to pad the sides but I didn't have any more!
I taped the card to the top of the box and to the bottom on the box. That's when I noticed the sides gaped.