I've used the code from the below link to run a macro automatically when the model is opened.
The issue i'm having is that its opening the userform before the model has fully loaded so i'm getting the 'no model open' response.
Sub Main(model As SldWorks.ModelDoc2)
Set swApp = Application.SldWorks
Set swModel = swApp.ActiveDoc
If swModel Is Nothing Then
MsgBox "No active part or assembly model found in SolidWorks." & Chr(13) _
& "Please load/activate a SolidWorks part or assembly model and try again.", vbExclamation