This happened before he became president, but he actually filed for and received a patent for one of his inventions.
Thomas Jefferson usually gets credited as America’s inventor-in-chief, but Abraham Lincoln is the only president to hold a U.S. patent. In 1849, shortly after the end of his lone term as a U.S. congressman, the Great Emancipator was issued U.S. Patent No. 6,469 for a device for “Buoying Vessels Over Shoals.” Lincoln had come up with the idea a year earlier after watching crewmen try to free a steamboat that had run aground on the Detroit River. Upon returning home to Illinois, he drew up plans for a pair of buoyant air chambers that could be attached to the sides of a boat and used to lift the vessel over shallow sections of river. Lincoln spent several weeks writing a description of the device and even built a scale wooden model, but while he received his patent, the invention was never put to use.
It's very exciting to find out that the list of famous people who did double duty as inventors is a fairly large one. Many of them never got the credit they were due, while others (like Harry Houdini) gave them away. Houdini's invention of a diving suit was given to the U.S. Navy.
Coffee out on the patio this morning, where the temps are supposed to be in thew 80s.