My metaphor for stuttering is that it is a low frequency of CPU in the "voluntary speech generating" cortex that sends instructions to the speech motor cortex. The reasons and mechanisms of that reduction are unknown even to the modern science. Therefore, the only way to speak fluently - is to find the right reduced "bitrate" for sending the data. Slowing the bitrate of syllables or even seperate sounds is easier by synchronizing it to the third party, like a real or imaginary metronome, or using rythmic movements of finger muscles. This "CPU" frequency can additionally be slowed down by your stress level, so keep that in mind too.