THe best I have found was to get some Marlboro flavored
juice from a vendor (i recomend MyFreedomSmokes & RockyMountainVapor) and get some Menthol Drops from JuicyLiquid. The menthol drops are just flavoring and not actual
juice, but they are STRONG! To get to what a marb menthol would be I would use 5 drops in a 10ml bottle and see what you think. Then if its not mentholy enough you can add another drop or 2 and retest.