Mechanical designer Jan Jurjen Zwaard designed the curved LEGO-compatible pieces. He actually spun off a series of designs made by fellow Thingiverse member Steve Medwin (shown below).
Speaking with 3D Print, Jan said, “I could not properly use [Medwin’s design] because I couldn’t remove the supports properly. Furthermore I missed some sizes and thought that the existing one was too solid. So I decided to recreate one in SolidWorks that would not need any supports and solve my other issues.” Jan plans to make a replica of his town’s water tower using his printed blocks.
You can download both Jan’s and Steve’s curved LEGO designs on Thingiverse.