Are there people who don't have .NET 3.5 installed?

Please don't suggest the "forget everything and code in Delphi" option.

I would suggest that it would actually be simpler.
No, let's put it this way. I'm interested in such a program – that's one thing. The framework is already installed (because of Paint.NET) – that's another. But, OUGHT... What specific functions from the framework do you need? Let's be honest, this is a simple program for calculations; it doesn't really need anything special. If you really wanted to, you could even make it a console application. And for a small program, would someone really have to install a framework? That's just not practical. Although, it depends on what exactly you want to do, of course, but it's probably just related to the interface, which is very easy to create in Borland products anyway, and the program remains lightweight.