I need a 5C collet holder 'block' that is round. Typically they are hexagonal or square. A machinist in the United Kingdom made one that is almost exactly what I need(see photo). The typical block is 2.75" long with a pin to prevent rotation. The round 'block' I need would have those features, but it would be 2.00" in diameter. Has anyone made something like this, or know where to purchase one?