How to Create a 3D Donut and Other Unusual Shapes in Your PCB Design

November 13, 2017 David Cousineau

3d design of unusual shapes


It is generally very simple to create realistic 3D mechanical shapes in Altium Designer® using the included Extruded, Cylinder, and Sphere shape types in the PCB Library editor. However, some shapes can be tricky. Although a hole cannot be cut out of any of the Altium-created shapes, a donut shape can still be achieved by essentially creating a closed “C” shape. Let’s take a look at how we can accomplish that.


coilcraft toroid inductors pcb design

The 3D Donut Shape Models These Coilcraft Toroid Inductors.


Create the Donut for Use in Your Designs

The dimensions for the donut are 1.5-inch outer diameter, 0.8-inch inner diameter, and 0.475-inch width.


In an open .PcbLib file, set the snap grid (G hotkey) to something large and easy to work with, in this case, 50 mils. Start the 3D body drawing mode from the Place/3D Body menu. In the 3D Body dialog, set the 3D Model Type to Extruded. The Body Side should default to Top side. The Layer should be any visible mechanical layer. The Overall Height is going to be the same as the width of the donut, 475 mils. Click OK to close the dialog and enter the drawing mode.


Using the (0, 0) point as a reference, click there to start the shape. Use <Shift+space bar> to toggle the drawing mode until the heads-up display shows the “Line 90/90 Vertical (Horizontal) with Arc (Radius: xx)” mode. The <space bar> (without the Shift) will toggle the direction of the arc. The <comma> and <period> keys decrease and increase the arc radius while the shape is being drawn (so chosen because the <and> symbols are on the same keys).


Use the <Shift+comma> or <Shift+period> to change the radius in steps of 10. Use these keys to set the radius to 750 mils (for a 1.5-inch diameter donut). Watch the heads-up display and move the cursor down to (750, -750) and click to lock in the first arc.


Drawing the First Arc in Altium Designer.


Continue on to (1500, 0) to add the next arc section.


Adding the Next Arc in Altium Designer.


Continue around the circle by steps of 750 mils to finish the outer diameter. Do NOT end the drawing mode at this point.


Continue All the Way Around. Do Not Yet End the Drawing Mode.


Since the outer and inner diameters of the donut are 1500 and 800 mils, the width of the ring is calculated as (1500-800)/2 = 350 mils. Move the cursor 350 mils inside the circle to begin drawing the inner diameter.


Position the Cursor to Draw the Inner Diameter.


Click to lock in the line. The inner diameter of the donut will now be drawn using a 400 mil radius. It is not necessary to adjust the radius setting, since the inner arc will be smaller. Move the cursor back along the same path used for the outer circle. Use the <spacebar> to swap the direction of the arc if it starts off the wrong way. The inner circle has a 400 mil radius, so watch the dx and dy values in the heads-up display to add the arc sections at 400, 400 increments.


Begin Adding Arc Segments.

Continue until the inner circle is completed.

Completed Inner and Outer Diameters.


Click the right-mouse button to complete the shape.

The Completed Donut in Two Dimensions.


Switch to 3D mode (View/Switch to 3D or 3 hotkey) to view the results.

Switching to 3D Mode Reveals the Completed 3D Toroid Shape.


Even without access to more complicated 3D mechanical editing tools, complex component 3D models can still be created with ease using the flexible and powerful editing capabilities in Altium Designer. Now that you have successfully created a 3D donut shape, the next step will be converting it into a STEP model so that you can utilize it as necessary in your designs.  

Interested to find out more about creating 3D donuts and other unusual shapes and converting them into STEP models? Download a free white paper today to learn more.


About the Author

David Cousineau

Dave has been an Applications Engineer for 20 years in the EDA industry. He started in 1995 at a mid-Atlantic reseller that represented PADS Software, ViewLogic, and a host of other EDA tools. He moved on to work directly for PADS Software, and stayed on as they were acquired by Innoveda and then by Mentor Graphics. He and a business partner formed a VAR of their own in 2003 (Atlantic EDA Solutions) to represent Mentor's PADS channel, and later on Cadence's OrCAD and Allegro products. Since 2008, Dave has been working directly for Altium and is based at his home office in New Jersey.

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