I’ve had a question about what I use to assist students in visualizing the manipulation of sounds. When I do my initial assessment, I use small wooden blocks. Nothing fancy, just blocks like these which probably came from my son’s toy collection.
During actual instruction, I teach kids to use their fingers for blending and segmenting. They touch their thumb to each successive finger (starting with the index finger) for each sound. (You model it on YOUR left hand so the sounds are presented in a left-to-right sequence). If kids want to use this strategy unobtrusively in their regular classroom, I teach them to tap single fingers in order on their lap (or on the edge of their desk).