Rope or Braid? Three strand rope is pretty easy. At the head end you need 3 spindles that turn in the same direction- a central sun gear with 3 equal size planets around it works fine. At the Tail end you need a spindle that turn in the opposite direction. So you twist the strands one way and wind then the other and get a nice laid rope. You do need cone with three grooves along it to run along as the rope is formed to keep the strands the proper tension.
We made rope as Boy Scouts with a simple rig we made with wood and coat hanger wire. The tail end crank was a brace and bit.
Now braid is MUCH more complicated. There have been braiding machines at a few of the New England shows. There used to be a fellow, whose name I now forget, that had a beauty he took to many shows. It consist of several spindles that follow a looping path that swings them around a set of gears. Remember the old Square Dance move where women went one way, guys the other, while handing off hands?