A melt system configured to convert a solid polymer (P) into a molten polymer (M), the melt system comprising: at least one melt unit having: a reservoir ; a melt grid positioned above said reservoir , said melt grid configured to expose said solid polymer (P) to a temperature sufficient to form a molten polymer (M) and to deposit said molten polymer (M) into said reservoir ; a hopper disposed above said melt grid and configured to hold a supply of the solid polymer (P), said hopper having a lower end , an upper end opposite said lower end , and a wall that extends from said lower end to said upper end , said lower end being proximate to and open to said melt grid , said upper end and said wall defining an internal chamber that holds said supply of said solid polymer (P); and a thermal isolation region disposed below said melt grid and above said molten polymer (M) in said reservoir , said thermal isolation region configured to thermally isolate said solid polymer (P) in said hopper from molten polymer (M) in said reservoir , wherein the thermal isolation region comprises an isolation chamber disposed below said hopper , characterized in that said hopper further has an access door disposed on said wall , said access door being moveable between a closed position where said hopper is closed and an open position where said internal chamber is accessible to receive said solid polymer (P). at least one melt unit having: a reservoir ; a melt grid positioned above said reservoir , said melt grid configured to expose said solid polymer (P) to a temperature sufficient to form a molten polymer (M) and to deposit said molten polymer (M) into said reservoir ; a hopper disposed above said melt grid and configured to hold a supply of the solid polymer (P), said hopper having a lower end , an upper end opposite said lower end , and a wall that extends from said lower end to said upper end , said lower end being proximate to and open to said melt grid , said upper end and said wall defining an internal chamber that holds said supply of said solid polymer (P); and a thermal isolation region disposed below said melt grid and above said molten polymer (M) in said reservoir , said thermal isolation region configured to thermally isolate said solid polymer (P) in said hopper from molten polymer (M) in said reservoir , a reservoir ; a melt grid positioned above said reservoir , said melt grid configured to expose said solid polymer (P) to a temperature sufficient to form a molten polymer (M) and to deposit said molten polymer (M) into said reservoir ; a hopper disposed above said melt grid and configured to hold a supply of the solid polymer (P), said hopper having a lower end , an upper end opposite said lower end , and a wall that extends from said lower end to said upper end , said lower end being proximate to and open to said melt grid , said upper end and said wall defining an internal chamber that holds said supply of said solid polymer (P); and a thermal isolation region disposed below said melt grid and above said molten polymer (M) in said reservoir , said thermal isolation region configured to thermally isolate said solid polymer (P) in said hopper from molten polymer (M) in said reservoir , wherein the thermal isolation region comprises an isolation chamber disposed below said hopper , characterized in that said hopper further has an access door disposed on said wall , said access door being moveable between a closed position where said hopper is closed and an open position where said internal chamber is accessible to receive said solid polymer (P). <EOS>