Symmetry is everywhere in engineering. Brackets have matching bolt holes on both sides. Enclosures have identical flanges left and right. Motor mounts have mirrored mounting patterns. Recreating these features manually on both sides of a design is slow, error-prone and completely unnecessary. The Mirror tool in Fusion 360 lets you build one side perfectly and duplicate it across a symmetry plane instantly — and once you start using it, you will find it hard to imagine designing without it. What Does the Mirror Tool Do? Mirror creates an exact copy of a feature, body, or component on the opposite side of a plane you choose. The original and the mirrored copy are linked — if you edit the original, the mirror updates automatically. This is what makes it so powerful for symmetric designs. Instead of maintaining two separate sets of features, you maintain one and let Fusion 360 handle the other side for you. Two Types of Mirror in Fusion 360 Fusion 360 has two separate Mirror tools and it is important to know which one to use for your situation. The first is Mirror under the Sketch menu, which mirrors sketch geometry — lines, circles and curves — within a 2D sketch. Use this when you are still in the sketching phase and want to mirror sketch elements before extruding them into 3D geometry. The second is Mirror under the Solid menu, which mirrors completed 3D features and bodies. This is the one most designers reach for when working with finished geometry, and it is the one this guide focuses on. How to Open the Mirror Tool Go to Solid in the top menu and click Mirror. You can also find it under Create in some versions of Fusion 360. There is no default keyboard shortcut for Mirror, but you can assign one in the keyboard shortcuts settings if you find yourself using it frequently — which you will. Step by Step — How to Use Mirror Step 1 — Build One Side First Before using Mirror, complete all the features on one side of your design. Add your extrudes, cuts, holes, fillets and any other features to that side. Mirror works best when your geometry is clean and fully defined before you duplicate it. Trying to mirror partially completed geometry often leads to errors or unexpected results that are harder to debug than simply finishing one side first. Step 2 — Open Mirror Go to Solid → Mirror to open the Mirror dialog. The dialog is straightforward and gives you all the options you need in one place. Step 3 — Choose What to Mirror In the Mirror dialog, the first choice is what you want to mirror. Features mirrors individual timeline features like a specific hole, cut or extrude — only that feature and its result get mirrored, not the entire body. Bodies mirrors an entire solid body across the plane, useful when you want to create a complete mirrored copy of your whole part. Components mirrors an entire component in an assembly context, used in multi-body and assembly designs. For most beginner use cases, Features or Bodies is what you need. Step 4 — Select Your Features or Body Click on the features or body you want to mirror. Selected items will highlight in the canvas. If you are mirroring features, you can select multiple features at once by holding Shift and clicking each one in the canvas or in the timeline at the bottom of the screen. Step 5 — Select the Mirror Plane This is the most important step. You need to tell Fusion 360 which plane to mirror across. You can use one of Fusion 360's default origin planes — the XY, XZ or YZ plane — by expanding the Origin folder in the browser and clicking the plane you need. You can also use any flat face on your model as a mirror plane, which is very useful when your symmetry line is not aligned with the default origin planes. If neither option works, you can create a construction plane at exactly the position you need and use that as your mirror plane. Step 6 — Click OK Your mirrored geometry appears instantly on the other side of the plane. Check the result from multiple angles to make sure it looks correct before continuing with additional features. Mirror in Sketch vs Mirror in Solid A common beginner question is whether to mirror in the sketch or mirror after modeling. Mirroring in the sketch is faster for simple symmetric profiles — if your part is perfectly symmetric and you can define the whole cross section in one sketch, draw half of it and mirror within the sketch before extruding. Mirroring in Solid gives you more flexibility — if your part has features added at different stages, like holes drilled after extrusion or fillets added later, mirroring the solid body or individual features after the fact is the cleaner approach that keeps your timeline more organized. Tips That Will Save You Time Use the origin planes when possible. Designing your part symmetrically around the default XY, XZ or YZ origin planes means you never need to create custom mirror planes — the ones you need are already there. Mirror sketch geometry for simple symmetric profiles — if you