It had been a family’s secret heirloom for five generations. And it will go on display Friday at the Indiana State Museum. An 11-inch wooden mallet inlaid with the initials “A.L” was made by Abraham Lincoln, who used it during his Indiana youth to make furniture. The tool has been in the family of one of Spencer County’s earliest settlers who were neighbors of the Lincolns. The mallet is being called an “incredible discovery” because it was crafted “by Lincoln’s own hands.”