One of those small but important experiments. The ongoing Welsh project requires walling similar to the above for some buildings. My preference these days is for Wills sheet (or similar; and more on that later) but the nearest item is the stone which is a little bit on the Cotswold side and definitely not as flat -faced as I wanted, with some blocks projecting out by quite a bit giving a heavy feel. Enter the trusty sanding board - usually used for shaping the mitre joints. A bit of scrap and a few minutes removes (along with some of the fingertips) about 10 thou of thickness. In other words the projecting areas and a lot of the 'cutting' marks. Much better.