giving volume to branching splines

Hi all.

I'm a fairly inexperienced lightwave user. What I would like to do is draw a network of branching wires, starting from a single wire that branches out into many. I prefer to draw them with the spline tool and then connect them by merging points. But if I do this, rail extrude won't follow the branches, just a single path. Also adding a branch stops the extrude orientating itself around the original path nicely.

I prefer drawing with the splines because it allows me to quickly draw the branches with nice curved lines but maybe this route isn't possible.

Thanks for any help,

John