How to create custom parameters?
We can create two kinds of custom parameters: by object or by document.
These parameters will be available only in the object where they have been created. They can be created and edited from the Properties Panel > Parameters.
These parameters will be available in every object created in the document. They can be created and edited from the Rhino Options > Document Properties > Parameters. Once created, we can check these parameters and assign them a value in the Parameters tab, inside the Properties Panel.