  We present a 48-element programmable phase plate for coherent electron waves
produced by a combination of photolithography and focused ion beam. This brings
the highly successful concept of wavefront shaping from light optics into the
realm of electron optics and provides an important new degree of freedom to
prepare electron quantum states. The phase plate chip is mounted on an aperture
rod placed in the C2 plane of a transmission electron microscope operating in
the 100-300 kV range. The phase plate's behavior is characterized by a
Gerchberg-Saxton algorithm, showing a phase sensitivity of 0.075rad/mV at
300kV, with a phase resolution of approximately $3\cdot10^{-3}\pi$. In
addition, we provide a brief overview of possible use cases and support it with
both simulated and experimental results.
