Lan can cong ba nep gap (con goi la luoi lan can cong tam giac hoac luoi lan can cong 3D) duoc lam tu soi thep Q235 thep carbon thap keo lanh. Sau khi duoc thang thang bang may thang va cat theo chieu dai co dinh, cac soi thep doc va ngang duoc han diem bang may han tu dong hoan toan de tao thanh mot tam luoi phang co kich thuoc dong nhat. Sau do, no duoc dua den may uon thuy luc CNC de ep cac nep gap hinh chu V doc tren tam luoi - doi voi chieu cao tu 1,8 met tro xuong, thuong co 3 nep gap (ten "cong ba nep gap" xuat phat tu day), va doi voi chieu cao tren 1,8 met, so nep gap tang len 4 nep. Sai so goc uon duoc kiem soat trong vong ±0,5°. Mot so san pham con duoc han them cac nep tang cuong o dinh tam giac de tang cuong hon nua do cung tong the. Sau khi tam luoi duoc hinh thanh, no se trai qua qua trinh xu ly chong an mon theo moi truong su dung. Cac phuong phap pho bien bao gom: ma kẽm nhung nong truc tiep (lop keo ≥ 60g/m²), son tinh dien sau khi ma kẽm (lop phu 80–120μm), hoac son nhung PVC sau khi ma kẽm. Cuoi cung, no duoc xac nhan boi "he thong ba kiem tra" bao gom tu kiem tra cua nguoi van hanh, kiem tra tuan tra cua doi truong va kiem tra cuoi cung cua bo phan chat luong rang do dong deu mat luoi, thang thang khung, do bam dinh lop phu va sai lech mau dat yeu cau, sau do duoc buoc va dong goi de giao hang cung voi cot hinh dinh nui (cot dinh diem) va cac thanh phan ket noi khac, duoc su dung rong rai trong hang rao bao ve nha may, co lap khu dan cu, an ninh duong bo va cac truong hop khac.