Emonty, yes, you can use any 306 but the bottom inside O-Ring will need to be smaller to grip and seal the Cart of the 306 or it will leak. I'm sure all the modders out there are going to go right after this and will be putting out the 306 & i06 Atty tanks very soon. This works and works very well, I would like to see a nice Delrin 306 sleeve for this Mod I came up with, like maybe Cherryvapes could make them long so we could cut them to size and in all different colors. Maybe one of the ECF Suppliers could have these made cheaply so we could all have a nice looking color inside of our tank instead of the stock orange looking carts or black that 306's come with.