'chaque lettre d'une cellule a une couleur
Sub coulCar()
For i = 1 To ActiveCell.Characters.Count
With ActiveCell.Characters(Start:=i, Length:=1).Font
Select Case ActiveCell.Characters(Start:=i, Length:=1).Caption
Case "a"
.ColorIndex = 5
Case "b"
.ColorIndex = 6
End Select
End With
Next i
End Sub