The cheapest option to build such a circuit would be to use a microprocessor and some shift registers to produce 50 outputs, then each output used to trigger a triac to switch ac to the coil, or as mentioned a fet if the coils are dc.
Or if you dont have the experience to build such a circuit, you could use standard on delay timers (there are different modes available), and use the output of one timer to trigger the next, triggering the first timer will start the cycle, much like a domino rally.
Industrial PLC controllers usually come with built in features for doing such things, a cam timer emulator is one of them, you'd specify 50 postions, then you have any output combination for each of the positions.