As explained in the section on unwrapping Revit elements, Dynamo has a parallel class library to Revit. This means special conversion methods need to be used to smoothly interoperate between the two.
Dynamo's Github wiki has a page which goes into detail on this topic, which can be found here. In short, it is worth being conscious of which geometry classes you're working with.
A good hint for understanding which geometry types you're working with are whether they're visible in the 3D background preview after being outputted from the node. Revit types won't be visible unless you use special conversion methods.
You can easily go between Dynamo and Revit geometry types using the conversion methods in Dynamo's API, but it's not always intuitive to know which ones to use. There is ToProtoType(),ToDSType(), ToLine(), ToPoint(), ToVector(), and ToXyz()!
The next sections will attempt to tackle the main kinds of geometry you're likely to encounter one-by-one.
Let's start with something simple - points! Points are defined in 3D space by their X, Y and Z coordinates and have no measurable dimensions.
To create a Dynamo point, we need to use the Designscript Library, which is a part of Dynamo. Dynamo Points are of type Autodesk.DesignScript.Geometry.Point.
If you output the below dynamo_point from a Python node it will immediately show up in Dynamo's 3D background preview.