Sub ПараСтолбовБезГраниц(Diapason As Range)
Dim f, t, str, n, rg
t = Diapason.Columns.Count
If Int(t / 2) <> t / 2 Then MsgBox "нечетное число столбцов в диапазоне"
For f = 1 To t Step 2
str = Diapason.Columns(f).Address
For n = 1 To Len(str)
If Mid(str, n, 1) = ":" Then rg = Left(str, n)
Next n
str = Diapason.Columns(f + 1).Address
For n = 1 To Len(str)
If Mid(str, n, 1) = ":" Then rg = rg & Right(str, Len(str) - n)
Next n
Diapason.Range(rg).Select
With Diapason.Range(rg)
.Borders(xlEdgeLeft).Weight = xlThin
.Borders(xlEdgeTop).Weight = xlThin
.Borders(xlEdgeBottom).Weight = xlThin
.Borders(xlEdgeRight).Weight = xlThin
.Borders(xlInsideVertical).LineStyle = xlNone
.Borders(xlInsideHorizontal).LineStyle = xlNone
.Borders(xlDiagonalDown).LineStyle = xlNone
.Borders(xlDiagonalUp).LineStyle = xlNone
End With
Next f
End Sub

Sub test()
ПараСтолбовБезГраниц ActiveSheet.Range("A1:H10")
End Sub