The Optimised hide tanner is a machine that can be built in the Invention Guild basement at level 111 Invention. It is an upgraded version of the Automatic hide tanner. It automatically converts hides into leather, even while the player is offline. The optimised hide tanner does not incur the normal coin/rune cost for converting hides into leather. Once the optimised hide tanner has processed some hides, the resulting leathers may be withdrawn via the machine management interface.