In my experience, having masks is a life-saver. I usually suffer from blocks, but instead of being blocked on a word, I just garble that word and move on to the next one, e.g. "(garble) you like bag with your milk?" and if the customer repeats, "would you (garble) bag with milk?". Usually people listen to words, not sentence structures, so as long as they hear "bag" and "milk" they understand 90% of the time. If you're wearing a mask, people would think that the mask does the garbling, not you, so you have an excuse for creating incoherent sentences. (Also, by having a mask on, the customer can't "read your lips" to infer that you are stuttering.) You could also complement your speech with gestures, e.g. holding a bag and pointing at the milk. Of course, I often fail to use these techniques, and end up in an embarassing situation (it gets worse if the other person treats me like a mentally retarded person or backs away thinking I am a drug addict). But at the end of the day, nobody really cares about it, which is slightly comforting. I guess, with enough time, we either develop emotional resilience towards stuttering, or at least become indifferent about it after suffering for so long. Perhaps it is at that stage that we can truly improve upon stuttering.