Motorised prop project feasibility

Hi all,

I am looking at making a prop weapon that has the ability to transform from one state to another. However, to retain accuracy to the source material, it requires the use of 15 motors each controlled by 2 limit switches. I am very new to all this, but in my research I have only found use of a small number of motors so I am unsure of the feasibility of my current idea. Also, due to the number of components required, I would preferably like to keep the costs as low as possible.

My current plan is to use 15 12V spur gear motors, controlled by 8 motor controllers (SN75440 or L293D type, each controlling 2 motors), with sequenced lead screw extension/retraction controlled by 28 limit switches (each with a resistor in a pull-up connection). There will be a maximum of 3 motors operating at a time. Due to the number of inputs required, I believe I will need to use a Arduino Mega 2560.

In case it is useful, this is a generalised version of the sequence:
The sequence will be initiated by a push button. One lightly loaded motor will run for the entire sequence. The first pair of motors will extend to their limit switch. Once both switches have been made, the first pair of motors will turn off, and the second pair will extend and so on. Once the last pair has extended, one motor from each pair will retract to their limit switch in turn (depending on my final mechanical design, I may need to add an additional 4 limit switches so these motors only retract to the middle of their range). An second push button will then reverse this sequence.

Without showing a circuit diagram (I’ll make that once I nail down the general design), is the idea and components suggested practical, or have I overlooked something and need to add additional components? Also, as both the motors and Arduino can be provided with 12V, can they both run off the same battery or would it be more practical to have separate batteries?

Components I'm looking at:
Spur Gear Motor
Limit Switches

Any additional suggestions would also be appreciated.

Regards
Neil.