One thing I learned about hydraulics is it uses Pascal’s principle. Because the liquid in the pipes is incompressible, the pressure must stay constant all the way through it, even when you’re pushing it hard at one end or the other.
One obstacle I encountered is that I wasn’t really accurate in the measurements, so it really bothered me for the rest of the project. We really had to be precise in drilling the holes so it can be put together perfectly.
My greatest success was that even though my measurements weren’t accurate, but I was able to fix it at the end: I adjusted the positions of the popsicle sticks from my original plan.