Walthers Cornerstone 933-3059 HO Planing Mill and Shed KIT NIBWalthers Cornerstone 933 3059 HO Planing Mill and Shed KIT NIB The Walthers Cornerstone Planing Mill and Shed are perfect for adding to 1900s and later sawmill operations. This set of structures, designed as accessories for the Mountain Lumber Co. Saw Mill (933 3058, sold separately) as well as other industries that use or work with lumber such as furniture factories. Inside this busy operation, rough cut timbers are run through planners and emerge as