You can make Log Cabin Clamshell with any of our Log Cabin Rulers:
Made with Log Cabin Ruler 8227 = 5½ʺ finished Log Cabin block makes an 11" finished Clamshell
Made with Log Cabin Ruler 8058 = 6⅞ʺ finished Log Cabin block makes a 13-3/4" finished Clamshell
Made with Log Cabin Ruler 8037 = 8¼ʺ finished Log Cabin block makes an 16-1/2" finished Clamshell
Made with Log Cabin Ruler 8038 = 11ʺ finished Log Cabin block makes an 22" finished Clamshell
Includes detailed step-by-steps and yardage for 6 Clamshell units for each size, plus a cutting plan for 6 sets in one color.