Thanks for the info!
I'm thinking about using two small Inner Diameter air cylinders at a max pressure of 80 - 90 PSI. That way I would only need a very small reservoir. I was thinking about a small fire extinguisher bottle or small propane tank mounted to the back of my Z plate. Something very small. The higher the working pressure, the smaller it can be. I don't really care if the top of the stroke force is off by 25lbs from the bottom of the stroke force.
I just don't know if the cheap EBay pneumatic cylinders will leak at those pressures. They say they will take the pressure, but will they leak, I don't know.
Gas struts would be the easiest, but they all have damping
. Hard to even see a damping spec on an inexpensive gas strut, they usually don't mention it.
Really awesome machine you have made!