To unpack it a bit, each stick is composed of 3 particles, one in the middle and two on either end. Two springs span from either end to the middle and a third spring spans from end to end to provide some bending resistance. The middle particles are all involved in medium range, medium strength separative forces (grey circles) and slightly longer range, low strength cohesive forces (invisible). At the same time the end particles are trying to converge through small range, high strength cohesive forces (magenta circles).
Platforms: C#, Grasshopper, Rhino