When Thomas Jefferson was not busy writing the Declaration of Independence, or the Statute of Virginia for Religious Freedom, he fancied himself an engineer.
This is a re-creation of Thomas’ improved design for the moldboard of an agricultural plow, the large, wooden part at the bottom responsible for lifting and turning the sod.
In his letter of 29 Dec 1794 to John Taylor , Thomas described his design as follows:
I have imagined and executed a mould-board which may be mathematically demonstrated to be perfect, as far as perfection depends on mathematical principles … it is on the principle of two wedges combined at right angles, the first in the direct line of the furrow to raise the turf gradually, the other across the furrow to turn it over gradually. for both these purposes the wedge is the instrument of the least resistance.Th: Jefferson
Thomas put his design into use on his plantation Monticello by 1794 with moldboards carved from wood. After using his design for several years, he committed the design to cast iron. In his letter of 4 May 1814 , Thomas requests John Staples of Richmond, Virginia, to cast 24 of this “plough of a form of my own”:
I send you the model of the mouldboard of a plough of a form of my own, and ask the favor of you to cast me two dozen in iron. I presume you will preserve the mould, as I shall probably call annually for a supply. I will thank you to have them ready as soon [a]s you can, and I will direct them to be called for. they had better be tied together in manageable bundles by bits of nailrod passing thro’ their holes. mr Gibson will be so good as to pay your bill for them. accept the assurance of my respect.
John Staples had known Thomas Jefferson since at least 1795. At the time of this letter, John “was superintendent of the state manufactory of arms and armory at Richmond, a position that carried the rank of major. He held the post until operations were suspended in about 1822. To defray the costs of running the manufactory’s foundry and boring mill, Staples initiated and promoted iron-casting services for the public.” 
You can read three letters from Thomas to John online at the National Archives.
John Staples was born in Albemarle, Virginia, in 1773. He was an inventor and engineer in his own right, being granted U.S. patents in 1802 and 1811 for “Improvement in Stills” (the liquid kind!) and “Pendulum Steam Engine”. In 1807, he served as a juror in Aaron Burr’s treason trial. 
Major John Staples (1773-1828) is 1st cousin 7x removed of MKS in the Spratlin branch.
President Thomas Jefferson (1743-1826) is 1st cousin 9x removed of MKS in the Knight branch.
 Moldboard Plow, monticello.org.
 Extract from Thomas Jefferson to John Taylor, monticello.org.
 Correspondence between Jefferson and Staples, monticello.org.