Not sure how you have your machine currently setup, if you could post a picture it paints a thousand words. Quite a lot of noise comes from vibration, so for instance hollow framework such as steel tubing/box section, vibrations into the floor if its wooden. So you may want to use a material called sorbothane,I use it quite a lot for 3d printers as the resonance carries without them as the feet. For instant noise reduction consider an enclosure, my machine is very noisy with the doors open for its enclosure and as soon as you close them its a huge reduction and my enclosure is a simple wooden box with acrylic windows in a wooden frame. If you do really want a sound proof setup an enclosure within an enclosure would realistically be the only option.