Flovv MoldLab — the complete guide

Geometry: female, male, or plug

Two choices set which surface the tool reproduces and whether you get a mold or a buck:

• ▸Tool controls: Female reproduces the outer (A / Class-A) surface of your part; Male reproduces the inner surface.
• ▸Composite output: a direct tool (Mold) is the negative you spray or lay up into; a Plug is a positive buck you laminate a fiberglass tool over.

Female and male molds and positive plugs are all supported today. (A matched two-sided mold is on the roadmap and not generated yet.)

Two schedules: part laminate vs. tool construction

Composite jobs plan two separate things, and it is worth keeping them distinct:

• ▸The part laminate — what you will manufacture: the layup process, resin chemistry, surface coat, and the stack of plies (with orientations for directional fabrics).
• ▸The tool construction — what the tool itself is made from: face material, billet stock, coating allowance, and cure-temperature limits.

The layup process you choose — hand layup, chopper-gun spray-up, wet layup + vacuum bag, vacuum infusion, RTM light, or out-of-autoclave prepreg — carries its own waste factor and fibre-fraction band, so the estimates track the way you will actually build the part.

Tool materials

Coating allowance (foam & board)

Foam and board tools get an epoxy skim coat, so MoldLab cuts the cavity oversize by the coating allowance (about 1.5 mm by default). The skim then lands the finished surface exactly on net shape. Aluminum and printed tools take no skim coat.

Billets, slabs, dowels & contour DXFs

Foam and board tools are not printed in one piece — they are sliced into slabs the size of one billet of stock. Pick a billet preset (XPS or EPS sheet/block, or tooling board) or set a custom size, and MoldLab slices the tool to fit, adds alignment dowel sockets between layers, and emits a per-slab cavity contour DXF (in the Contours/folder) you can cut on a hot-wire, router, or CNC. Cut the slabs, dowel and stack them into the block, then skim-coat. You can also CNC the STLs directly instead of cutting from the DXFs.

Surface (skin) inputs

You can hand MoldLab an open surface — a zero-thickness skin or panel, the way aircraft and body panels are often modelled — not just a closed solid. It stitches the surface patches together and thickens the skin on its back side, leaving the front (tool) face exactly as you drew it, so the tool reproduces your surface faithfully. A tilted skin is automatically rotated square to the pull direction before the tool is built, so the block hugs the skin face-on and the cavity spans the whole tool face — a real drape, not a slanted slot. Surface skins are a composite-only input: a printed two-part mold needs a solid part and rejects skins up front.

When your upload contains two or more separate solids, MoldLab pauses before building and asks what to do rather than silently guessing. (Only GLB/GLTF files — and STEP, which is converted to GLB first — carry the structure MoldLab can pre-scan; a single-solid STL or OBJ always builds straight through.) Bodies are listed largest-first by volume.

Your choices

• ▸Mold the largest body — the historical default; ignores the rest.
• ▸Mold one body — pick a specific body from the list and mold just that one.
• ▸Mold all — MoldLab fans the file out into one job per body, queued in body order.

With Mold all, each body becomes its own job with its own mold, preview, and per-body report — so a five-body assembly gives you five molds and five reports, one per part. A single worker builds them in sequence, so they queue up behind one another.

Placing the funnel before the build

In Mold settings, “Pour funnel position” gives you three ways to place it:

• ▸Auto (recommended) — the default: MoldLab picks the safest spot over the part.
• ▸Compass presets — center, any of the four edges, or any of the four corners, seen from above, plus fine-tune X/Y offsets in millimeters.
• ▸“Pick in 3D” — after upload, the job pauses and shows your part in an interactive viewer; click the exact funnel spot, and optionally switch to Air-vents mode to click your own vents (up to 8 — click a marker to remove it). The build resumes once you place.

Moving the funnel and vents on a finished mold

You don’t have to get it right the first time. On a finished printed or silicone mold, open the 3D viewer and choose “Move funnel / vents”:

• ▸Click the top of the mold where the funnel should go — re-click to move it.
• ▸Switch to Air-vents mode to add up to 8 vents; click a vent marker to remove it.
• ▸Rebuild — MoldLab regenerates the mold with your placements. A rebuild is a new mold and counts like a new job (a free-trial rebuild uses one of your trial molds).

How your picks are honored

• ▸Placed vents replace the automatic ones entirely — exactly your vents, nothing else. Placing no vents keeps automatic venting.
• ▸A click that lands off the part is snapped to the nearest valid spot over the cavity, and the report tells you it was snapped.
• ▸A vent that can't hold a 5 mm gap from the funnel or from another vent is dropped — the mold still builds with the rest, and the report lists what was dropped and why.

Honest limits: funnel and vent placement is for printed and silicone molds only. The aluminum CNC mold base keeps its sprue at the press center for now — user-routed gates are on the roadmap — and composite tooling is open molding, so it has no funnel at all. Vents cap at 8 per mold.

File formats — and the honest notes

You can download the same job as STL, 3MF, OBJ, PLY, GLB, or STEP.

• ▸STL, 3MF, OBJ, PLY, GLB — mesh formats that carry the geometry exactly as generated. Print from the STL or 3MF set.
• ▸STEP — a faceted conversion (one planar face per triangle, decimated for CAD tools to swallow) meant for reference and CAM, not exact printing.
• ▸STEP for CNC plates is the exception — the mold-base pieces export as true analytic BREP (real planes, cylinders, and cones you can reference in CAM); only the cavity region is faceted from the mesh.