This paper has two related parts. In the first part we derive using classical methods a formula for the configurational force on a magnetoelastic wall. In the second part we formulate the problem of the motion of a small-scale cantilever made of ferromagnetic shape memory material and driven by a remotely applied field. The motion is caused by the movement of twin boundaries and, consequently, the energy stored by the cantilever scales as the thickness, rather than the thickness cubed. We derive equations of motion for the cantilever. The usual balances of linear and rotational motion are found to be insufficient to determine the motion, and this is remedied by the postulation of a kinetic law that relies on the formula for the driving force on a magnetoelastic wall given in the first part.