Copper Pipe Casting

Time to cast copper pipes. No other way. 

Take a plastic pipe. Pour plaster of paris inside it. Take another bigger pipe enclosing the plastic pipe and pour plaster of paris on between both the pipes. After few hours (plaster of paris will dry) take out the plastic pipe. Let the whole thing dry for a few days. We have a mold for casting copper pipes. Cast as many pipes as we need. 10 ft pipes should be good enough. Place in a shell and tube? Or continuos?

Do same thing for silicone pipes.