A system for producing a cranial operculum for a living being, comprising: an acquisition device configured to define an area of planned removal of cranial bone (Ap) on the skull of the living being based on diagnostic images of the patient and on the target zone for a surgical procedure; a first 3D detection device configured for 3D detection of a skull cap shape (Fc) of a skull cap to be removed within said area of planned removal of cranial bone (Ap); a second detection device configured to detect margin points (P_MRG) of a margin of a crater in the cranial bone following removal of a part of skull cap included in said area of planned removal (Ap); an electronic digital fabrication device configured to produce three-dimensional objects; and a processing unit in data communication with said acquisition device, said first 3D detection device, said second detection device for detecting the points of the margin of the crater in the cranial bone and said 3D electronic digital fabrication device, wherein said processing unit is configured to define a 3D digital model of the cranial operculum based on the skull cap shape (Fc) and the skull thickness (Sc) detected by said first 3D detection device and based on the margin of the crater in the cranial bone detected by said second 3D detection device, the processing unit comprising: • a first processing module configured to generate a first 3D digital model of the cranial operculum processed on the basis of said area of planned removal (Ap), said skull thickness (Sc) and said skull cap shape (Fc) in said area of planned removal (Ap) wherein said first 3D digital model of the cranial operculum is generated before carrying out a surgical procedure of craniotomy; • a second processing module configured to generate a 3D digital margin model (M_Mrg) on the basis of the points (P_MRG) of the margin of the crater in the cranial bone detected by said second detection device; • a third processing module configured to generate a second 3D digital model of the operculum processed on the basis of said first 3D digital model and said craniectomy margin model (M_Mrg); and • a transmission module configured to transmit said second 3D digital model to said electronic digital fabrication device. an acquisition device configured to define an area of planned removal of cranial bone (Ap) on the skull of the living being based on diagnostic images of the patient and on the target zone for a surgical procedure; a first 3D detection device configured for 3D detection of a skull cap shape (Fc) of a skull cap to be removed within said area of planned removal of cranial bone (Ap); a second detection device configured to detect margin points (P_MRG) of a margin of a crater in the cranial bone following removal of a part of skull cap included in said area of planned removal (Ap); an electronic digital fabrication device configured to produce three-dimensional objects; and a processing unit in data communication with said acquisition device, said first 3D detection device, said second detection device for detecting the points of the margin of the crater in the cranial bone and said 3D electronic digital fabrication device, • a first processing module configured to generate a first 3D digital model of the cranial operculum processed on the basis of said area of planned removal (Ap), said skull thickness (Sc) and said skull cap shape (Fc) in said area of planned removal (Ap) wherein said first 3D digital model of the cranial operculum is generated before carrying out a surgical procedure of craniotomy; • a second processing module configured to generate a 3D digital margin model (M_Mrg) on the basis of the points (P_MRG) of the margin of the crater in the cranial bone detected by said second detection device; • a third processing module configured to generate a second 3D digital model of the operculum processed on the basis of said first 3D digital model and said craniectomy margin model (M_Mrg); and • a transmission module configured to transmit said second 3D digital model to said electronic digital fabrication device.