Quick answer
A drain hole is useful only when it reaches the intended cavity through a practical passage in print orientation. Map every cavity, find low and high regions, inspect bottlenecks, plan washing and curing access, then repeat the check after supports, plugs, splits, or scaling.
- Count cavities before counting holes.
- Drainage and ventilation depend on print orientation.
- The narrowest passage controls the practical route.
- Any later geometry edit can invalidate a previously safe path.
Think in connected paths, not visible circles
A hole can look open from the outside yet terminate in solid material, reach only one of several cavities, or connect through a passage too narrow to wash effectively. Validate the complete path through the final shell.
Complex sculpts may contain pockets created by limbs, clothing, supports, or hollowing offsets. Each disconnected pocket needs an explicit decision: connect it, open it independently, or keep that region solid.
Evaluate openings in print orientation
- Low regions
Give liquid a route out of the cavity as it forms and during post-print drainage.
- High regions
Provide a path for displaced air when geometry would otherwise act as a closed cup.
- Bottlenecks
Measure the narrowest part of the route, not only the visible entrance diameter.
- Support interaction
Check whether internal or external supports obstruct access or create new pockets.
- Finishing access
Plan flushing, inspection, post-curing light, and any plug or cosmetic repair.
A cavity-by-cavity placement workflow
- Lock print orientation
Drain and vent behavior changes when the model rotates.
- Map all cavities
List connected volumes, sealed pockets, and narrow necks.
- Mark candidate openings
Choose accessible low and high regions while protecting visible surfaces and thin details.
- Trace each route
Confirm the opening reaches the correct cavity with adequate passage width.
- Review cleaning access
Make sure liquid, wash fluid, and curing light can reach the cavity in practice.
- Recheck the final export
Repeat connectivity after holes, supports, plugs, splits, and scale are final.
Why there is no universal number or diameter
Material viscosity, cavity volume, orientation, passage length, printer process, washing method, and finishing plan all affect practical drainage. Use manufacturer guidance as a starting constraint, then evaluate the actual model and workflow rather than copying one number into every project.
Do this in Meshworthy
Give every cavity a verifiable status.
Meshworthy maps cavities and traces their outside connections so a visible hole cannot produce a false pass.
- 01Generate the cavity graph
See disconnected cavities, connecting necks, and outside openings.
- 02Apply print orientation
Review low points, high points, and cup-like regions in the chosen orientation.
- 03Place candidate holes
Protect cosmetic surfaces and Keep Solid details while testing practical routes.
- 04Inspect bottlenecks
Follow each route and review its narrowest passage and accessibility.
- 05Revalidate the final geometry
Re-run the graph whenever another operation changes the shell or openings.
Common questions
Technical answers and limitations.
Are two drain holes always enough?+
No. Two openings can still serve only one cavity while another remains sealed.
Can a vent hole also drain?+
Possibly, depending on orientation and path geometry, but evaluate both liquid flow and air replacement rather than relying on the label.
Should I add holes before supports?+
Plan them early, then verify again after supports and all geometry edits because access can change.
Primary references
Verify the underlying guidance.
Apply these checks in Meshworthy
Inspect the model, review the operation, and verify the export.
Meshworthy applies these checks locally on your Mac and does not upload your model.
Map resin cavities and drain paths ↗