Tinkercad is a free, browser-based modeling tool from Autodesk where you build objects by combining basic shapes and cutting with hole shapes. This tutorial builds a small robot figure with a flat base, then exports it as an STL for your slicer. The short version: stack boxes into a robot, turn two small boxes into holes for the eyes and mouth, select everything, press Union Group, check it, and export.
A toy has two jobs: it must print without fuss, and it must not break into pieces small enough to swallow. Both are decided in the design, so this guide uses a wide base, chunky parts and no thin spikes, and ends with a short toy-safety section based on the US Consumer Product Safety Commission (CPSC). All dimensions are examples; adjust them freely. Tool names and shortcuts come from Tinkercad’s help center (checked in 2026).
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The robot toy in eight steps
- Create a new 3D design and check the units and snap grid.
- Add the base: a flat box that gives the toy a wide footprint.
- Add the body box on top of the base area.
- Add the head box, overlapping the body slightly.
- Add two arms, overlapping the body.
- Add eye and mouth holes by turning boxes into hole shapes.
- Select everything and press Union Group, then inspect the result.
- Export an STL and open it in your slicer.
Tinkercad tools you will use
| Action | How it works in Tinkercad | Shortcut |
|---|---|---|
| Move | Drag the shape, use the arrow keys (one snap-grid increment per press) or drag the arrow handle to raise or lower it | Arrow keys |
| Scale | Drag the handles, hold Shift for proportional scaling, or click a dimension and type a value | Shift |
| Rotate | Drag the rotation handles; the inner circle steps by 22.5 degrees, the outer area by 1 degree, and Shift gives 45-degree steps | Shift |
| Hole | In the Inspector, switch a shape from Solid to Hole; any shape can be toggled | Inspector |
| Union Group | Combines solid shapes; hole shapes in the group take material away. Select at least two shapes first | Ctrl/Cmd+G |
| Align | Aligns two or more shapes by center, top or bottom along width, depth or height | L |
| Mirror | Flips a shape across an axis | M |
| Drop to Workplane | Lowers a shape until its lowest point touches the workplane | D |
| Ruler | Shows dimensions and sets exact distances between shapes | R |
Set up the workspace
Sign in at tinkercad.com and create a new 3D design from your dashboard. Open the Workspace settings (bottom right) and check the units. The Snap Grid, which controls how far a shape moves per drag step or arrow key press, defaults to 1 mm in a new design, and smaller values allow more precise placement. If you know your printer’s bed size, the Workspace settings also have presets to resize the workplane to a printer’s build platform, which you can save as a custom preset.
Build the robot step by step
| Part | Tinkercad shape | Example size (X × Y × Z, mm) | Placement |
|---|---|---|---|
| Base | Box | 36 × 30 × 4 | On the workplane, centered |
| Body | Box | 28 × 22 × 30 | On the workplane, centered on the base so it overlaps it |
| Head | Box | 24 × 20 × 16 | Centered on the body, raised so its bottom sits about 2 mm inside the top of the body |
| Arm (two) | Box | 6 × 8 × 20 | Outer edge flush with the base edge, overlapping the body by about 2 mm |
| Eye holes (two) | Box set to Hole | 4 × 4 × 4 | Half inside the front face of the head |
| Mouth hole | Box set to Hole | 12 × 4 × 3 | Half inside the front face of the head, below the eyes |
- Base. Drag a Box onto the workplane, click a dimension and type the size, or use the Inspector. The base sets the footprint: a wide, flat base is what keeps a tall toy from tipping over and gives the print a large contact area with the bed.
- Body. Add a second Box at 28 × 22 × 30 mm. Use the Align tool to center it on the base. Because both sit on the workplane, the body automatically overlaps the base.
- Head. Add a third Box. Drag the arrow handle above it to lift it, or use the Ruler tool to set the distance, until it sits about 2 mm inside the top of the body. Overlap is important: shapes that only touch along a face can leave a weak or open joint, so push them into each other.
- Arms. Add one Box at 6 × 8 × 20 mm on the workplane, with its inner edge inside the body. Duplicate it (or copy and paste) and use Mirror to flip the copy to the other side. The arms stand on the base, so they print without support underneath.
- Eyes and mouth. Add small Boxes at the sizes in the table. In the Inspector, switch each from Solid to Hole. Position them so about half of each box sits inside the head’s front face. Only the part inside the head cuts material.
- Union Group. Select every shape (drag a selection box over them, or hold Shift and click) and press Union Group or Ctrl/Cmd+G. Solid shapes add together, and the hole shapes take material away. Tinkercad’s own advice is to group with Union Group because it gives a more realistic preview of the printed part. Check that the eyes and mouth are indented and nothing floats.
- Personalize. Add a chunky ear, a belt or a chest panel, each overlapping the body. Keep every added piece thick, and avoid pencil-thin antennas, which are the easiest things to break.
Check the design before exporting
Tinkercad’s printing best practices list the checks that matter most at this stage:
- Use basic shapes, and check your units and the dimensions of your parts.
- Group shapes with Union Group for a realistic preview of the printed part.
- Make sure all parts touch the workplane and lie flat on it, not floating above it.
- Avoid overhangs, and rotate the part so more of its surface touches the workplane.
- Avoid parts or walls that are too small or thin; Tinkercad suggests wall thicknesses of at least 1.5 mm.
This robot follows those rules: a flat base, stacked boxes with no overhangs, and every wall well over 1.5 mm. The eye and mouth pockets are the only horizontal features, and they are small and shallow. If you add features, the support-free design guide explains how to keep them printable.
Toy safety: small parts
The CPSC’s small parts rule (16 CFR part 1501) exists to prevent deaths and injuries to children under three from choking on, inhaling or swallowing small objects. It covers products intended for children under three, and it uses a test cylinder that approximates the size of a young child’s fully expanded throat: if an object fits entirely inside the cylinder in any orientation, it is a small part. Pieces that break off during use-and-abuse testing can also count, so what matters is not only the toy as designed but what it becomes when it breaks.
- For a child under three, treat any printed toy as unsuitable unless it has no small parts, including pieces that could snap off. The cylinder dimensions are in Figure 1 of 16 CFR 1501.4, which you can check against any detachable or breakable part.
- Prints can split between layers, so thin or protruding features are the likeliest to snap. Our guide on weak layer adhesion explains why. Keep arms and ears thick and attached over a wide area.
- This site makes no claim that any filament is safe for toys, for mouthing or for food contact. Check the filament manufacturer’s safety information, and if you sell or give toys to others, check the toy-safety rules where you live; this tutorial is not a compliance guide.
Export and slice
Press Export on the top toolbar. Under Include, choose everything or only the selected shapes, then choose the file type: Tinkercad offers OBJ, STL or GLTF for 3D printing. For a single-color toy, STL is enough. All shapes are grouped as a single part on export, which is why you group and check first. You can also send the model to a supported printer app from the 3D Print tab of the Export panel, after setting up the app and connecting your printer.
Open the file in your slicer and check the size against your design before slicing; the export and slicing checklist covers units, formats and orientation. Print the base on the bed, as in the model. For the first print, use the default profile for your printer and filament. If you want a different modeling approach, the free software comparison shows the alternatives.
Common mistakes in Tinkercad toys
- Shapes that only touch. Overlap parts by a couple of millimeters before grouping; faces that just touch make weak joints.
- Forgetting to group. A hole shape cuts nothing until it is grouped with the solid it overlaps.
- Holes that miss the solid. A hole that does not overlap the body cuts nothing. Check the preview after grouping.
- Floating parts. Anything hovering above the workplane without support from the shapes below will not print. Use Drop to Workplane (D) or overlap it with the body.
- Stretching a shape unevenly. Hold Shift while scaling for proportional resizing, or type exact dimensions.
- Skipping the next step. The model is only a file until it is sliced. Start with your first 3D model if you want the full path from measurement to print.
Frequently asked questions
Is Tinkercad free, and do I need to install it?
Tinkercad describes itself as a free collection of online tools, and it runs in a web browser, so there is nothing to install. Free use requires accepting its terms of service, and you sign in to an account to start and save designs.
Why did my hole shape not cut anything?
In Tinkercad a hole shape only removes material once it is grouped with a solid shape. Select the solid and the hole together and press Union Group (Ctrl/Cmd+G), and make sure the hole actually overlaps the solid. If it still seems solid, drag the hole deeper into the shape and group again.
Should I export STL or OBJ from Tinkercad?
STL is the usual choice for a single-color toy. Tinkercad offers OBJ, STL and GLTF for 3D printing, and PrusaSlicer, for example, ignores material and texture data in OBJ files on import, so OBJ gives you no benefit here.
Can I print this toy without supports?
The design is built to avoid supports: a flat base on the bed and stacked boxes with no overhangs, apart from small eye and mouth pockets. If you add features that stick out sideways, check them in the slicer preview and see our support-free design guide.
Sources
- Tinkercad Help Center: Best Practices for 3D Printing Tinkercad Models, Exporting 3D models for 3D Printing, Sending 3D models to your 3D printer, Using Workspace Presets
- Tinkercad Help Center, tools: Union Group, Using the Inspector, Rotating shapes, Scaling shapes, Align, Snap Grid
- CPSC: Small Parts (FAQ)
- Cornell LII: 16 CFR 1501.4, method for identifying toys and other articles intended for use by children under 3 years of age which present choking, aspiration, or ingestion hazards because of small parts
- Prusa Knowledge Base: Supported file formats
