I see my project breaking down into three components. In order of priority, they are:

Probe

The first piece I would like to build is a “probe,” the piece that actually comes in contact with human skin. I imagine this will be a rod with a vibration motor and a cloth covering, which is then wired up to control vibration speed and rhythm.

Placement

The second piece is the mechanism for controlling the location of the probe on the arm. Ideally I would like the probe to move on three axes, similar to a CNC machine, but two axes (along the arm and down onto the arm) are more likely. A pressure sensor would be helpful here to standardize sensation.

Frame

The third piece is the frame. Initially I was conceiving this as a wearable piece, but I am not sure how large and heavy the placement piece will be. If possible, I’d like to build a frame out of PVC piping to hold the device on an arm.