I took one argos value stool http://www.argos.co.uk/static/Product/partNumber/6006606/Trail/searchtext%3ESTOOL.htm
sat it upside down on the padding to draw round it to give me exact size of cushion
and then I had a piece like this
and then....... well to be honest it all became a bit fuzzy (that's why you shouldn't drink vodka while you craft)
when I came downstairs this morning I had this
so either I managed to finish it or the elfs did it after I went to bed.