How to create own dynamic type or dynamic object in C#?

Question

There, is for example, ViewBag property of ControllerBase class and we can dynamically get/set values and add any number of additional fields or properties to t

Answer 1

ExpandoObject is what are you looking for.

dynamic MyDynamic = new ExpandoObject(); // note, the type MUST be dynamic to use dynamic invoking.
MyDynamic.A = "A";
MyDynamic.B = "B";
MyDynamic.C = "C";
MyDynamic.TheAnswerToLifeTheUniverseAndEverything = 42;