Assembly AND parts required. Requires 2 M5 nuts and 2 M5x35mm countersunk screws. Maker's recommended print layout : Female part (the big one) should be printed laying down with the shallowest dovetail parallel AND towards to the buildplate .(The raft build plate adhesion is ESSENTIAL for this one ) The male part has been designed to be printed standing upright on it's dovetail The hatch should be printed with the widest part on the buildplate Image for reference available on the product page. Maker's recommended print settings : Material : PLA 1.75mm .Nozzle size 0.4 Layer height 0.2mm Wall line count 4 Top/bottom thickness : 0.8 Top layers : 4 Bottom layers  : 4 Infill density : 40% Infill pattern : Triangles Printing temperature : 215°C Build Plate temperature : 80°C Generate supports : ON Support placement : Everywhere Support overhang angle : 60° Build plate adhesion type : RAFT. Once printed, press the nuts into their sockets inside the female part (strength may be required , tight fit) then slide the hatch into it's dovetail (once again tight fit) . End step : slide male part into the female part and clamp the assembly around a picatinny rail and screw the screws through the male part and the nuts trapped inside the female part. Tests during  both airsoft and range sessions (.223) successfull. Under barrel foregrip done.