One tool for every opening that needs covering: HVAC vents, drain grates, speaker grilles, PC fan guards. Six patterns — louvered slats, honeycomb, round perforations, radial rings-and-spokes, swept turbine blades, or a solid blanking cap — on a rectangular or round body. For wall and duct work, size the grille to the opening and add the insert skirt (a press-in collar) plus a cover brim that stops flat against the wall, with optional screw holes. For PC fans, just pick the preset: 80, 92, 120 or 140mm sets the frame and puts the four screw holes at the exact standard spacing. Print tip: prints flat with no supports. For airflow grilles keep the web between openings at 2mm+; for guards that fingers will poke, the radial pattern is the strongest.