In some cases it could be very useful to develop your own activities for UiPath. Therefore a longer time ago I presented CShell as one possibility. Here is another possibility with the great text editor Notepad++ and the plugin CS-Script. With this software it is also not necessary to use Visual Studio.
After the installation of Notepad++ open from Plugins menu the Admin tool. Choose CS-Script and press Install button.
After the successful installation of CS-Script plugin you get a tiny configuration hint.
Now you can code your C# program with Notepad++ with code completion.
And you can execute your C# program inside Notepad++.
It is also possible to debug your C# program line by line and to view the content of variables in an additional Debug window.
Notepad++ and CS-Script plugin are a great combination to develop C# programs and therewith activities for UiPath. Both are easy to handle, easy to install and both needs tiny space.