The following is an example to create the folder structure you described with 5 digit padding and only taking inputs from the part numbers you select before running it. Note that you need to set a Reference to the Microsoft Scripting Runtime.
Code:
Sub MakeFolders()
'requires reference to Microsoft Scripting Runtime
Dim subFolders() As String, sPath As String, aCell As Range
Dim iNum As Long, sCell As String, sFolder As String, i As Integer
Dim sPathF As String, sPathSubF As String
Dim fso As New FileSystemObject
sPath = "C:\Temp\"
subFolders = Split("Calculations|Capacities|Correspondence|Inspections", "|")
For Each aCell In Selection
sCell = Trim(aCell.Value)
iNum = Mid(sCell, 3)
sFolder = "PN" & Format(iNum, "00000")
sPathF = sPath & sFolder
If Not fso.FolderExists(sPathF) Then fso.CreateFolder sPathF
For i = LBound(subFolders) To UBound(subFolders)
sPathSubF = sPathF & "\" & sFolder & " - " & subFolders(i)
If Not fso.FolderExists(sPathSubF) Then fso.CreateFolder sPathSubF
Next i
Next aCell
End Sub