Public Sub test()
' Grab first layer in ArcMap
Dim pMXDocument As IMxDocument
Set pMXDocument = ThisDocument
Dim pMap As IMap
Set pMap = pMXDocument.FocusMap
Dim pLayer As ILayer
Set pLayer = pMap.Layer(0)
' Create an instance of ArcScene
Dim pDocument As IDocument
Set pDocument = New esriArcScene.SxDocument
Dim pApplication As IApplication
Set pApplication = pDocument.Parent
pApplication.Visible = True
' Add a layer to ArcScene
Dim pSXDocument As ISxDocument
Set pSXDocument = pDocument
pSXDocument.AddLayer pLayer
End Sub