[roadcat]

I am sure that it would be fairly easy to get some air, gas or electric piston parts that simply presses that compression bag on a fixed cycle.

There are plans online to build your own ventilator by using a 3D printer to make most parts, supplemented with some electronics, and downloadable code. The creator posted warnings that it is use at your own risk and is only meant to demonstrate that they can be built at home, but you should use medical facilities. Video of it is impressive.

[Elsie]

Aquarium air pump?