well heres a run down.
Take 1 pool cue , and shape sand to a dread shaped object.
Bolt it into a section of white pvc tubing ( white is important )
Pour silicone in.
Then i cut a 1 inch wide section of the tube out the whole length, this enabled me to flex the pvc and pop out the silicone inner.
i then removed the pool cue from the silicone mould, i then realised i would have trouble getting the foam dred out, so my solution was to cut down the length of the silicone mould on 1 side.
reinsert the silicone back into the pvc tube with the cut of the silicone facing the inside of the tube ( opposite the missing 1 inch section ) this holds the cut closed fairly well as long as i have a look down the tube to make sure its closed.
Pour your foam
wait 30 mins
Pray the humidity and temp has not alterd too much. ( or they wrinkle and collapse on themselves )
removed silicone and pop out your dred, with hopefully minimal seem line, which doesnt really does not matter as you could hide the seem facing backwards if you get a bad one.
Booie/Hez and others probably have much much more efficient ways of making foam dreds, but this worked for me.