Hi all.
Was in the garden centre today, found this and thought of you all.
It is made for lining ponds, refered to as a 'stone liner'
And is £16.25 for 1x0.40m (3.2ftx1.3ft)
You can get 1x1m (3.2ftx3.2ft) size for £37.25
Just thought I would show you all.