Blowing Bubbles with Thomas the Train

While shopping at wal-mart last night I ran across the clearance aisles! Who does not love these aisles? Anyways I found some bubbles. My son is in a bubble stage and we use them often in his ABA therapy for positive re-enforcement. He loves them. 

Another good thing about this is he loves Thomas the Train. They had others such as spider man and Jake and the Neverland Pirates. 
Thomas is a whistle as well. You pour some bubbles in the blue track little pot thing, then dip Thomas' chimney into the bubbles and blow. The bubbles come out and the whistle blows. He loved it! 

I just wish we could teach him how to blow bubbles on his own. Any suggestions?