Fill (Beta)

Updated October 22, 2026 10:11

Learn how to use the Fill tool to create complex geometry using boundary profiles, guide curves, or connected curve networks. Explore continuity settings, geometry requirements, and best practices for creating smooth transitions.

What is the Fill tool?

You can use the Fill tool to create complex, smooth solid geometry using boundary profiles, guide curves, or a combination of both. Fill is useful for creating smooth transitions between bodies, bridging irregular gaps, and closing multi-sided openings.

Fill generates solid geometry from the selected inputs and lets you adjust continuity to control how the resulting surfaces connect to surrounding geometry.

Fill is useful for creating complex geometry such as:

Smooth transitions between parts of a model
Rounded or dome-like shapes
Custom curved surfaces

How to use the Fill tool

Before you start

Prepare the geometry you want to use with Fill:

Boundary profiles – Identify the faces or profiles that define the borders of the opening you want to fill.
Guide curves – Prepare sketch edges, sketch splines, or curve items to connect the geometry or control its shape.
Input connections – Make sure your inputs connect to form a continuous network.

Note: Depending on your geometry, you can use boundary profiles, guide curves, or both.

Using the Fill tool

To create geometry with Fill:

Go to Tools > Fill.
Select the boundary profiles, guide curves, or combination of both that you want to use.
Optional: Use the continuity badges to adjust how smoothly the resulting geometry connects to surrounding faces.
Optional: To review or modify your selections and check their status, select Fill again from the menu to open the parameter card.
To finish and exit the tool, click anywhere in an empty area of the modeling space.

Fill boundaries and guide curves

Fill uses boundary profiles, guide curves, or a combination of both to define the shape of the resulting surface. Boundary profiles define where the surface connects to existing geometry, while guide curves help control its shape.

To create a valid Fill surface, the selected inputs must form a connected network. How you prepare and connect these inputs also affects the shape and continuity of the resulting surface.

Boundary profiles

Boundary profiles define the borders of the opening or void you want to fill. When preparing boundary profiles:

Connected boundaries: Boundary profiles do not need to form a closed boundary on their own. You can connect them with guide curves to define the resulting geometry.
Supported geometry: You can use supported body geometry and sketch profiles as boundary inputs.
Resulting geometry: Selected profiles are cloned as boundary faces of the new solid body, which spans between the profiles to fit their geometry.
Continuity references: Fill uses adjacent body faces to calculate G0, G1, and G2 continuity. For sketch profiles without adjacent body faces, it uses an imaginary reference ribbon extruded perpendicular to the sketch plane.

Guide curves

Guide curves help define and control the shape of the geometry created by Fill. When preparing guide curves, consider the following:

Connections: Guide curves can connect boundary profiles, refine the resulting shape, or form a connected network without boundary profiles.
Supported geometry: You can use sketch edges, sketch splines, or curve items as guide curves. Body edges cannot be selected as guide curves.
Continuity: How guide curves connect to other curves and surrounding geometry can affect the smoothness of the resulting surface. To learn more, visit Understanding curve and surface continuity.
Curve quality: Avoid unintended sharp changes in direction where guide curves meet. Even when the curves form a connected network, their shape and continuity can limit the smoothness of the resulting surface.

Preparing input geometry

Before using Fill, make sure your selected profiles and guide curves form a connected network that defines the geometry you want to create.

Check connections – Make sure selected profiles and guide curves meet at the intended locations without unintended gaps.
Plan the curve network – Start with the simplest arrangement that defines your shape. Add curves where you need more control.
Check from different angles – Verify that curves really connect in 3D space, rather than only appearing to touch from one view.

Fill continuity settings

You can adjust continuity in Fill to control how the resulting geometry connects to surrounding surfaces. Use the continuity badges to choose how smoothly the surfaces meet at each boundary.

Boundary continuity

The following continuity settings are available:

G0 (Positional) – Connects surfaces at a shared boundary without matching their direction, which may form a visible corner or sharp edge.
G1 (Tangent) – Matches the direction of the surfaces at the boundary for a smooth transition.
G2 (Curvature) – Matches the direction and curvature of the surfaces for an even smoother transition.

For more information about these settings and how they affect geometry, visit Understanding curve and surface continuity.

Adjust continuity using badges

By default, Fill uses G0 continuity. You can use the continuity badges to adjust individual boundaries or apply the same setting to all applicable boundaries.

Individual badges – Use the continuity badge for a boundary to change its continuity setting.
Set All – Applies your selected continuity setting (G0, G1, or G2) to all applicable boundaries.

Note: Each continuity badge offers G0, G1, and G2 options. However, not all settings may produce a valid result, depending on the surrounding geometry.

Continuity requirements and limitations

The continuity you can achieve depends on the geometry used to create the Fill result.

For smoother transitions, consider the following:

Adjacent surfaces – The surrounding geometry must support the continuity setting you want to apply.
Guide curves – Their shape and connections can influence the smoothness of the resulting geometry.
Input geometry – Gaps, sharp changes in direction, or incompatible inputs can prevent Fill from achieving the requested continuity.

Continuity controls for different input types

The available continuity controls depend on the type of geometry you select. Some boundaries have continuity badges that let you adjust how Fill connects to surrounding geometry, while others don't require a separate continuity setting.

Input geometry	How Fill handles continuity
Shared edges between selected profiles	No separate continuity setting is needed, so no continuity badge appears.
Body edges next to unselected faces	Continuity is adjusted relative to the neighboring unselected face.
Sketch profile edges	• Continuity can be adjusted using the available badges. • Continuity is calculated relative to the faces of an imaginary body created by extruding the selected sketch profile perpendicular to the sketch plane.
Sketch edges and curve items	• Continuity can be adjusted using the available badges. • Continuity is calculated based on boundary segments that intersect the edge. • For segments generated from standalone guide curves or sketch lines, continuity is calculated relative to a reference ribbon derived from neighboring connected segments.

Parameter Card and History Settings

Shapr3D records the tools you use as steps in History, allowing you to revisit and modify them later. Each History step stores its parameters, which you can access through the parameter card.

You can adjust these parameters while using the tool or reopen the parameter card from History after completing the step.

Adjust Fill parameters

While using Fill, you can open the parameter card to review or modify your selections. To open the parameter card, select Fill again from the menu.

The following parameters are available:

Boundary Profiles – Review or modify the boundary profiles used to define the Fill geometry.
Guide Curves – Review or modify the guide curves used to control the shape of the resulting geometry.

To learn more about using and customizing the parameter card, visit Parameter Cards.

Edit Fill in History

To modify an existing Fill step:

Open the History sidebar.
Select the Fill step to edit to reopen its parameter card.
Review or modify the boundary profiles and/or guide curves used in the Fill step.
To finish editing, click anywhere in the modeling space.

To learn more about managing and editing steps in History, visit History.

When to use the Fill tool

Common Fill use cases

Use Fill when you need to create geometry from connected boundary profiles, guide curves, or curve networks, and control how the result transitions into surrounding geometry.

Common uses include:

Fill gaps or openings in existing geometry
Create smooth transitions between surrounding surfaces
Create rounded or dome-like surfaces from a boundary
Create complex surfaces using guide curves to control the shape
Create surfaces from irregular boundaries that are difficult to build with simpler surface tools

Fill vs. Loft

Both Fill and Loft can create complex, smooth geometry, but they use different inputs and are suited to different workflows.

	Fill	Loft
Purpose	Creates solid geometry across enclosed areas, including irregular gaps and multi-sided openings.	Creates geometry between two or more cross-sectional profiles.
Input geometry	Uses boundary profiles, guide curves, or connected curve networks to define the resulting geometry. All profiles must lie along the boundary of the void to be filled.	Uses two or more cross-sectional profiles arranged in sequence to define the resulting shape.
Guide curves	Uses guide curves to connect inputs or control the resulting shape. Guide curves can also form the entire input network.	Uses optional guide curves to control how the geometry transitions between profiles.
Best for	Irregular openings, multi-sided gaps, and complex transitions between existing geometry.	Shapes defined by a sequence of cross-sections and smooth transitions between profiles.

Best practices and troubleshooting

Follow these recommendations to prepare your geometry, improve Fill results, and resolve common modeling issues.

Best practices

Check continuity between input curves – Make sure connected curves have the appropriate continuity for the intended shape. Learn more in Curve continuity in Understanding curve and surface continuity.
Avoid protruding sharp corners – Prepare boundary geometry without sharp corners that extend outward, as these can make it difficult to generate a smooth surface.
Keep profiles along the boundary – Avoid selecting cross-sectional profiles that divide the volume you want to fill. All profiles should lie along the boundary of the void.
Use guide curves to refine the shape – If the resulting geometry appears too flat or doesn't have the shape you want, add guide curves to control its curvature and overall form.
Adjust continuity gradually – Start with G0 continuity, then increase to G1 or G2 for individual boundaries. Adjusting one boundary at a time can help identify where higher continuity settings cannot be achieved.
Trim overlapping geometry – If surrounding faces extend beyond the area you want to fill, use Imprint Edge to divide the geometry and select only the required regions.
Refine Fill through History – If your design changes, reopen the Fill step in History to adjust boundary profiles, guide curves, or continuity settings without recreating the step.

Troubleshooting common issues

Issue	How to resolve it
Fill fails when selecting internal profiles	Check that the selected inputs define the intended connected network. If you are using internal cross-sectional profiles, try selecting the profiles and guide curves that define the opening or transition instead.
Guide curves are disconnected	Make sure guide curves connect to the intended boundary profiles or other curves. Check the connections from different viewing angles to find gaps in 3D space.
Fill fails with the selected input geometry	Check that the selected profiles and guide curves form a connected network that defines the intended result. Try simplifying the inputs to identify an incompatible connection.
Fill cannot use faces without boundary edges	For seamless geometry, such as spheres or torus-shaped bodies, use Imprint Edge to create selectable boundaries before using Fill.
G1 or G2 continuity fails at sharp corners	Sharp corners between adjacent faces may prevent higher continuity settings. Consider adding a small fillet to soften the corner before using Fill.

Practice with Fill example projects

Explore the example projects below and follow the video guides to practice different ways of using Fill.

Project	Project file	Video guide
Create an elliptical dome: Use Fill to create a curved dome surface from an elliptical boundary.	Download >
Create a smooth lofted dome surface: Use Fill with G1 and G2 continuity to create a smooth surface that blends into an existing lofted dome.	Download >
Create a smooth corner transition: Use Fill to create a smooth surface where rounded transitions meet at a corner.	Download >
Create a rounded pocket transition: Use Fill to create a smooth surface transition inside a recessed pocket.	Download >
Create a backpack surface transition: Use Fill to connect straight and curved boundaries, adjusting continuity to control the surface transition.	Download >
Create a soap bottle surface transition: Use Fill to connect curved boundaries and create a surface that blends into the surrounding bottle geometry.	Download >
Create a curved soap bottle surface: Use Fill to create a surface across an open section of a soap bottle, following the surrounding curved geometry.	Download >
Shape a soap bottle surface: Use Fill to shape a surface within the bottle's existing boundaries.	Download >
Connect two pipes: Use Fill to create a connecting surface between two pipe openings.	Download >
Connect a hairdryer handle: Use Fill to create a smooth surface transition between the handle and main body of a hairdryer.	Download >
Create a thermometer housing: Use Fill to create a smooth surface transition between intersecting cylindrical forms.	Download >
Create a smooth handle transition: Use Fill to connect curved boundaries and create a smooth surface transition on a handle.	Download >
Connect three pipes: Use Fill to create smooth transitions between three intersecting pipes.	Download >
Create a rounded remote housing: Use Fill to create a curved end surface that follows the shape of a remote control housing.	Download >
Create a rounded package end: Use Fill with guide curves and boundary continuity settings to shape a rounded end surface.	Download >
Create a water canister surface: Use Fill to create a smooth surface transition between the body and handle of a water canister.	Download >