A molding device , comprisi ng: a mold , having a mold cavity , a feeding port in communication with the mold cavity ; and a pressure regulating system , including: a first gas conduit , in communication with the mold cavity ; a first valve , disposed at the first gas conduit and configured to control gas injection from a gas source through the first gas conduit to the mold cavity ; a pressure sensing unit , configured to sense the pressure within the mold cavity ; a second gas conduit , in communication with the mold cavity ; and a second valve , disposed at the second gas conduit , configured to control the discharging of gas out of the mold cavity , wherein the mold further includes an inner sidewall , an inner top wall , and an inner bottom wall opposite to the inner top wall defining the mold cavity , said feeding port is disposed at the inner top wall , said second gas conduit is configured to discharge gas from the mold cavity , and said inner sidewall of the mold cavity has a junction point , wherein the first gas conduit is in communication with the mold cavity via the junction point , characterized in that said first gas conduit is in communication with the mold cavity through a plurality of first pores disposed at the mold; said second gas conduit is in communication with the mold cavity through a plurality of second pores disposed at the mold; a number of the plurality of second pores is substantially greater than number of the plurality of first pores. a mold , having a mold cavity , a feeding port in communication with the mold cavity ; and a pressure regulating system , including: a first gas conduit , in communication with the mold cavity ; a first valve , disposed at the first gas conduit and configured to control gas injection from a gas source through the first gas conduit to the mold cavity ; a pressure sensing unit , configured to sense the pressure within the mold cavity ; a second gas conduit , in communication with the mold cavity ; and a second valve , disposed at the second gas conduit , configured to control the discharging of gas out of the mold cavity , a first gas conduit , in communication with the mold cavity ; a first valve , disposed at the first gas conduit and configured to control gas injection from a gas source through the first gas conduit to the mold cavity ; a pressure sensing unit , configured to sense the pressure within the mold cavity ; a second gas conduit , in communication with the mold cavity ; and a second valve , disposed at the second gas conduit , configured to control the discharging of gas out of the mold cavity , wherein the mold further includes an inner sidewall , an inner top wall , and an inner bottom wall opposite to the inner top wall defining the mold cavity , said feeding port is disposed at the inner top wall , the mold further includes an inner sidewall , an inner top wall , and an inner bottom wall opposite to the inner top wall defining the mold cavity , said feeding port is disposed at the inner top wall , said second gas conduit is configured to discharge gas from the mold cavity , and said inner sidewall of the mold cavity has a junction point , wherein the first gas conduit is in communication with the mold cavity via the junction point , said first gas conduit is in communication with the mold cavity through a plurality of first pores disposed at the mold; said second gas conduit is in communication with the mold cavity through a plurality of second pores disposed at the mold; a number of the plurality of second pores is substantially greater than number of the plurality of first pores. <EOS>