Trim a point grid

I'm trying to write a definition for a relatively simple concept that my friend has. He wants to have a set of clyinders touching and moving along their height axis thus creating a 3d form.

I first created a grid of points that would be suitable for setting up the cylinders so they touch eachother. I've done it with some math.

Then the only way i thought of projecting these points to a surface was by letting lines generate from every point and intersecting the line with the surface.

The next step i thought was limiting the points so the appear within one closed surface, so i could avoid trimming the projection surface, but i'm unable to. Any thoughts?