3D Modeling Cartoon Character - Part 2: Solid Hair and Combine Parts to Single Mesh

In this post, we will continue to model our cartoon character’s head. The first section will focus on the hair object. We have drafted a surface as the hair in the last teaching. However, the mesh is not 3D-printable because it has zero thickness. Thus, it is necessary to thick the surface to produce a certain before it can be used for 3D printing. We must further modify it to be a solid object.

After finishing the hair, you can follow the second section to integrate the hair into the head. But it is optional for you to fuse multiple components to be a single solid. If your 3D printer software can handle mesh overlapping, you may skip the process and follow the third section to add ears to the head object.

This post will cover:

Convert hair to a solid object
Merge hair with head object
Modeling ears

3D Modeling Cartoon Character - Part 2: Solid Hair and Combine Parts to Single Mesh 3 — Hair model built in the last post

meina hair hair tip zoom in — Zoom in of a hair tip

⬢ Convert hair to a solid object

There are multiple ways to thicken meshes. Most 3D modeling software contains a function to convert an open surface to a close solid; typically, it offsets surfaces with a uniform thickness. You can try and evaluate the outcome; however, you won’t obtain a high-quality mesh by the algorithm if the surface is complex with many features. If so, I will recommend you using another way to produce a well-structured mesh. The following instructions will show how to use a combination of manual operations to thicken the hair workpiece.

Step 9

Thicken Hair tips

Start from the hair bunches, repeatedly thicken each segment and transform the blocks into hairy shapes

Open the option of Polygon Extrude tool (press X key), and switch Mode to Thick

Move/rotate/scale the mesh to rough out the shape, e.g. thinner at the tip and thicker at the trunk.

Toggle the smoothness (press Tab key), and check the finished shape

Rotate the view angle to the inner side of the hair, then delete the cap polygon from the extrusion as shown in the figure

Step 10

Merge Hair bunches

Try to form a smooth periphery on inner side of Hair

Zoom in the gap between two hair bundles. Then, select the edges from a pair of opposite meshes, and then use Bridge tool to patch the gap

Step 11

Form inner surfaces of Hair

Extrude the edges from the inner periphery and stitch the new meshes to a dome-like shape as the inner surface of the hairpiece

Select an edge section along the rim, then use Polygon Extrude tool to gradually extend the inner segments

Use Bridge tool to join adjacent meshes

Check point

At the end of this task, the Hair part should look similar to the 3D object shown in the above picture. It has not finished yet, as it is still an unclosed mesh. If you’ve seen hats and hairs for LEGO Minifigures, they’re designed with an interlock for you to snap them to Minifigures’ heads. Similarly, we need to leave some spaces for further designing the connection between the two pieces.

You can consider the following 3 approaches :

It will be the laziest approach. Before export as an STL file, you will need to continue stitching the inner surface of the hair component to form a closed mesh. Next, deform the shapes or adjust the positions of either the hair or the head object to make an overlapping between the two volumes. In this way, we will leave the mesh merging operation to 3D printing software or post-processors.

For example, Ultimaker Cura is capable of handling STL multiple objects. You can enable the Union overlapping volumes settings in the Print settings. Nevertheless, there are always at risk of producing invalid geometries when slicing overlapping meshes. Moreover, not all 3D printer software possesses a similar feature. You can try to make a single solid with Meshmixer as an alternative.

Just like the LEGO bricks, you can create a joint between the two parts. The small, cylindrical bumps on top of most LEGO bricks are called studs. Likewise, you can add a cylindrical object and merge it to either the hair or the head component. Meanwhile, use a slightly larger cylindrical object to tap a hole on another one.

However, high precision is required to produce an interference fit. It often takes several times to test and adjust the tolerance for 3D printed parts, to make it work. Joint making will be covered later in the series; however, it won’t be used here.

It is the safest way to build a 3D printable object. You will combine multiple 3D objects to a single entity. You connect all meshes or merge two or more bodies to a manifold and watertight mesh in your 3D modeling software. You take control of your mesh before output it to your 3D printer, like fixing all mesh issues including bad geometries, holes, disconnected faces, and mesh intersections.

3D printing tips: Tips for successful modeling – Shapeways

⬢ Merge hair with head object

Before reading the following instructions, you can merge the two solid objects by attempting the Combine or Union function in your 3D modeling software. The algorithm works well sometimes, while sometimes fails or generate strange results. Despite this, always try to use the simplest, quickest, and easiest modeling way first. But, you can also follow the stupid technique below to manually join two objects.

Step 12

Change Head to an open mesh object

Cut a hole at the top of the skull

Step 13

Resize and optimize the hole in Hair

Use Scale tool to reduce the hole size and flatten the vertices to lay on the same plane. Then, use Polygon tools to adjust the number edges along the boundary to be the same as that on the skull

Step 14

Align and connect the two separate surfaces

Select both boundaries and use Move tool to modify the relative position between them. Next, Use Bridge tool to join the gap between the two meshes

A closed mesh object will be obtained after completing the above steps.

Step 15

Inspect and fix polygons

Use Flip tool to view inside out the cavity helps you spot bad geometries, e.g. mesh intersections, twisted surfaces, etc.

⬢ Model outer ears

Step 16

Set Symmetry

Choose Action Center > Axis as Origin, and then Set Symmetry as X

Step 17

Determine the position of ears

Unhidden all mesh faces and the backdrop image, and change the View and Shading settings to show back the grid, then select the polygons at the ear position

Step 18

Form the shape of ears

Tips: Hide those hair segments from the view while editing the ear section

Use Extrude tool (press X key) to produce new segments and then pull outwards to rough out the size of ears
Gradually move the edges and vertices to deform the mesh to a helix structure

Toggle the visibility of the hair segments to verify the geometries of the ears
Adjust the geometries to avoid mesh intersections

Check point

The second note of this tutorial series is up to here. You should learn the know-how and the skills for making a solid 3D-printable model from polygons and meshes. There are many ways to manipulate vertices edges and faces of meshes; therefore, I recommend you keep updates with the latest software and professional modeling approaches. That helps you to improve and simplify your workflow. The next post will move to model the neck, and the body of the figure.

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