Because T-Splines is "end-of-life," most professionals have transitioned to newer workflows:
T-splines represent a powerful tool in the world of computer-aided design and engineering, offering a flexible and efficient way to model complex surfaces. Their applications span multiple industries, contributing to advancements in design, manufacturing, and visualization. The specific version you mentioned, T-Splines v.4.0.r11183, would be a part of this evolving technology, aimed at providing users with robust tools for T-spline modeling and analysis. t-splines - v.4.0.r11183 download
Suggested adoption checklist
Since Autodesk has officially retired T-Splines, the original website and official download pages are no longer active. Because T-Splines is "end-of-life
Since Autodesk has removed the primary download links, you can try the following methods to retrieve the installer: Autodesk Account contributing to advancements in design
: A common community-vetted source for the installer is an archived link from the Wayback Machine: TSplines4.0_r11183ForRhino.exe.