# 👂 Earrings: Mirroring, Posts and Matched Pairs
## Learning Objectives
By the end of this lesson you can:
- Explain why a mirrored pair beats two hand-modeled earrings, and when a mirror is actually required.
- Set up a Mirror modifier driven by a Mirror Object empty so you control the gap between the two earrings.
- Build a post at a real-world gauge, align it perpendicular to the earring back, and merge it into the body cleanly.
- Check that front and back detail read correctly on both earrings before you render.
## Quick Review
In the pendant lesson you built a body, a bail and a controlled wall thickness, then checked the silhouette from the front and the side. Earrings reuse exactly that discipline. The new difficulty is that ==everything you build now has to agree with a partner object==, so a small modeling error gets duplicated instead of hidden.
## Theory
### A pair is one decision made twice
Most earring designs are symmetric: the left and right earrings are identical pieces, not mirror images of each other. Some designs are asymmetric (a curve that sweeps to one side, a letter, a crescent), and those genuinely need a left and a right version.
Either way, you model one earring and let the software produce the second. There are two ways to do it:
| Approach | How it works | Risk |
| --- | --- | --- |
| Mirror modifier | One object, modifier generates the opposite side live | Needs a correct mirror plane and clipping settings |
| Duplicate + rotate 180° | Two separate objects, one rotated around the vertical axis | Edits no longer stay in sync, and the second earring shows its back |
For a portfolio pair, the Mirror modifier is the safer default because every edit you make afterwards updates both earrings at once.
### The Mirror Object empty
A Mirror modifier without a Mirror Object mirrors around the object's own origin. That is fine for a single symmetric shape, but for a pair you want the mirror plane to sit in empty space between the two earrings. Add an empty, place it at the world origin, then in the Mirror modifier set **Mirror Object** to that empty.
Now the empty is the mirror plane:
- Place the earring 10 mm to one side of the empty and the pair sits 20 mm apart.
- Move the empty and the whole pair shifts; move the earring and the gap changes.
- Enable **Clipping** so vertices cannot cross the plane, and **Merge** so vertices that land exactly on the plane weld together.
### Posts at real-world gauge
A post is not a decorative detail, it is a functional part with standard dimensions:
- Diameter: **0.8 mm** (20 gauge) or **1.0 mm** (18 gauge). Anything much thicker will not read as a wearable earring.
- Length: about **10 mm** behind the earring back, enough for a friction back.
- Orientation: perpendicular to the flat back surface, not tilted, unless the design deliberately angles the earring.
Build the post as a cylinder with 8 to 12 sides, shade it smooth, and merge it into the earring body so there is no visible seam. A small bevel or fillet where the post meets the metal keeps the joint from looking like a weld.
### Front and back detail
This is the gotcha that catches almost every beginner. If you build the second earring by duplicating and rotating it 180° around the vertical axis, one earring shows its front to the camera and the other shows its back. The pair only looks matched if the back detail mirrors the front detail.
With the Mirror modifier across the plane between the earrings, both earrings present the same face. That is why a mirrored pair automatically satisfies "identical front and back detail" for symmetric designs.
```cloze
A standard earring post is about {{c1::0.8 to 1.0 mm}} in diameter.
The Mirror modifier uses a {{c2::Mirror Object}} empty to set the mirror plane in world space.
Before mirroring, apply scale with {{c3::Ctrl+A}} so both sides keep even thickness.
Enable {{c4::Clipping}} so geometry cannot cross the mirror plane.
Duplicating and rotating 180° means the second earring shows its {{c5::back}} to the camera.
```
```mermaid
flowchart TD
A["✏️ Model one earring"] --> B["📏 Apply scale"]
B --> C["🪞 Add Mirror modifier"]
C --> D["🎯 Point Mirror Object at the empty"]
D --> E["🔩 Build and merge the post"]
E --> F["🔍 Check front and back detail"]
F --> G["🖼️ Render the matched pair"]
```
## Worked Examples
### Example 1: Mirroring one earring into a pair
```steps
1. Select the earring and press Ctrl+A, then Scale. Confirm Object Mode > N panel shows Scale 1.0, 1.0, 1.0.
2. Add > Empty > Plain Axes, and in the N panel set its location to 0, 0, 0.
3. Select the earring, go to Modifier Properties > Add Modifier > Mirror.
4. Set the Axis to X (the axis running between the two earrings).
5. Set Mirror Object to the empty you just made.
6. Tick Clipping and set Merge distance around 0.001 m.
7. Move the earring to X = -0.010 m. The pair now sits 20 mm apart.
8. Orbit to the front view. Both earrings should look identical, not front and back.
```
### Example 2: Building a post
```steps
1. Place the 3D cursor at the center of the flat back of the earring.
2. Add > Mesh > Cylinder, set Vertices to 12, Radius to 0.0004 m, Depth to 0.010 m.
3. Rotate the cylinder 90° so it points straight back along the earring's normal.
4. In Object Mode, check the post axis against the earring back with an orthographic side view.
5. Select the post, then Shift-select the earring, and join with Ctrl+J.
6. Go into Edit Mode, select the ring of vertices where the post meets the body, and press M > Merge by Distance.
7. Add a small Bevel (0.1 mm, 2 segments) to the joint ring, then shade smooth.
```
### Example 3: Matching the pair before render
Press Shift+D on nothing, instead just toggle the Mirror modifier off and on. With it off you see one earring; with it on you see the pair. Render a front orthographic view at 512 px and check three things: the two silhouettes are the same width, both posts point away from the camera, and no shading seam appears on either side. If the silhouettes differ, you have a non-uniform scale that was never applied.
## Guided Practice
These exercises continue the capstone brief you set up in Module 1.
**Exercise 1 (5 min).** Your brief says the earrings hang 22 mm apart. Where does the earring object go, given an empty at the world origin?
Show answer
The empty is the mirror plane, so each earring sits half the gap away: 11 mm, at X = -0.011 m. The modifier generates the partner at X = +0.011 m, giving a 22 mm gap.
Show answer
Halve the radius to 0.0004 m so the diameter is 0.8 mm, a standard 20 gauge post. An oversized post reads as a rod, not jewelry, and it makes the earring look like a model rather than a product.
Show answer
Replace the duplicate with a Mirror modifier plus a Mirror Object empty at the center, so both earrings present the same face. The trade-off: the design is now a true mirror pair, so any deliberately asymmetric sweep will flip on the second earring. If the design is meant to be asymmetric in the same direction, use two linked duplicates instead and rotate each earring separately so both fronts face outward.