DrawSTL Open Editor

Vent & plumbing

A main drain cover made to your measurements

This page generates a domed cover for the drain at the bottom of a pool or pond and exports it as an STL. Enter the cover diameter or side length in millimetres, choose the dome height, top pattern and number of screws, and the model is recalculated in the browser.

The cover has three parts: a flat seat ring that screws to the floor, an upright side band that lets water in from the side, and a low dome with an opening pattern on top. When a leaf or cloth sticks to the top, water still passes through the openings in the side band.

Open in editor See the sizes

Free, no sign-up. Change the sizes in millimetres and download the STL.

Round domed main drain cover with radial slots on top, a solid centre hub and vertical slots in the side band

Ready-made variants

Each variant is the same template with different settings. Follow the link and the editor opens with those values.

Adjustable sizes

These values are edited in the editor's template panel. A number outside the range is clamped to the nearest limit automatically.

SizeRangeDefault
Shape
Frame shapeCircle, SquareCircle
Dimensions
Diameter / side120–300 mm200 mm
Dome height0–40 mm12 mm
Side band height6–60 mm15 mm
Shell thickness1.6–6 mm3 mm
Corner radius *0–60 mm10 mm
Pattern
Top patternSpiral, Radial, Venturi, Round holes, Honeycomb, Square grid, Parallel linesRadial
Slot / hole size1.5–15 mm4 mm
Rib thickness0.8–8 mm2 mm
Slot count *4–6032
Twist angle *0–80 °30 °
Outward flare *0–30.7
Hub Ø0–100 mm30 mm
Side pattern
Side patternNone, Round, Honeycomb, Square, Vertical slots, Spiral (slanted slots)Vertical slots
Side opening *2–20 mm5 mm
Side rib *0.8–10 mm2 mm
Solid top/bottom band *1–30 mm2 mm
Slant (from vertical) *0–45 °30 °
Mounting
Seat ring width8–40 mm16 mm
Seat ring thickness2–8 mm3 mm
ScrewsNone, 4, 6, 84
Screw hole Ø *3–8 mm5 mm
Countersink *On / OffOn

Sizes marked with a star appear in the panel only when the related shape, style or option is active.

What it is used for

  • Drain cover for a garden pond, water feature or fountain basin
  • Replacement cover for a gravity drain without pump suction
  • Template and test fit for an old cover that is no longer sold

Printing tips

Orientation
Prints with the flat seat ring on the bed and the dome facing up. In this orientation the underside of the dome shell spans open air.
Layer height
Use 0.2 mm, or 0.16 mm for fewer visible steps on the dome.
Infill
30-40% infill, 4 perimeters; people may step on it, so the shell should print solid.
Supports
Supports are needed. The dome shell, or the top plate of a flat cover, sits over an empty space; use supports from the build plate only.
Material
Choose ASA for chlorinated water and sun, PETG for shaded spots. PLA softens in water and cracks at the screw holes.

Tips

  • Keep support density at 10-15% so it breaks away cleanly from under the dome.
  • Size the screw holes for stainless screws; the countersink is on the top face.

Safety: suction outlets

On a main drain connected to pump suction, the cover is a safety part. It must be tested and certified against hair, limb and body entrapment, for example to ANSI/APSP-16 in the US or EN 13451-3 in Europe. A printed cover is not tested to those standards, so it should not be used on a suction outlet in a pool where people swim.

This template suits garden ponds, water features, gravity drains without suction and temporary use. It also helps you measure a broken cover and test the fit before ordering a certified replacement.

Size, pattern and screw layout

Size is the outer diameter of the seat ring or the side of the square frame. The ring must be wide enough to carry the screw heads; screws are spaced evenly around its middle. On a square frame, four screws go to the corners.

  • Radial and spiral slots: leaves and coarse debris
  • Venturi: slots that widen outward for more flow
  • Honeycomb and round holes: even strength on a flat cover
  • Hub: the solid disc in the middle, a place to step

Frequently asked questions

Can I print it without supports?

No. The dome or flat top plate closes an empty space above the side band, and a slicer cannot bridge it. Flipping it over does not help, because then the outside of the dome touches the bed at a single point.

Can I make one for a square drain?

Set the frame shape to square and give it a corner radius. The dome and side band stay round; only the seat frame that screws to the floor becomes square.

The cover flexes too much. What should I change?

Raise the shell thickness to 3.5-4 mm, add a little dome height and enlarge the hub. A domed shape flexes less than a flat plate of the same thickness.

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Set the sizes to fit your part

Open the template in the editor, enter your values and download a print-ready STL. No account needed.

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