The Prusa i3 series consists of open-source fused deposition modeling 3D printers, manufactured by Czech company Prusa Research under the trademarked name Original Prusa i3. Part of the RepRap project, Prusa i3 printers were named the most used 3D printer in the world. The first Prusa i3 was designed by Josef Průša in 2012, and was released as a commercial kit product in 2015. The latest model (MK3S+, as of November 2020) is available in both kit and factory assembled versions. The Prusa i3's comparable low cost and ease of construction and modification has made it popular in education and with hobbyists and professionals. Since the i3 series is open source, there have been many variants produced by companies and individuals worldwide.