I use a lot of references. Check out these padlocks. See how the shackle's like a gradient that follows a path and bends around a corner? That's what I'm trying to do.

Here's a quick thing I made. I know it looks stupid, but it shows how the typical linear gradient is appropriate for something like the body of the lock, but not for the curve of the shackle. You can see the radial gradient almost starts to work, but you don't get the control you need to stretch, shape, and position it into an arch.

enter image description here

  • 1
    The arc in the bottom right version looks like a nearly defunct fluorescent lamp.
    – user82991
    Commented Nov 21, 2019 at 2:01

2 Answers 2


Simply use a thick stroke as opposed to a shape, and apply a gradient to the stroke.

enter image description here

You can expand the gradient stroke afterwards, resulting in a gradient mesh object.

You can also stack multiple strokes via the Appearance Panel to add additional gradients. Here I've added a second stroke with a gradient to indicate shadowing on the lower portion...

enter image description here

  • I was going to suggest gradient mesh, but this is a LOT easier. I learned something today! Commented Nov 20, 2019 at 22:25
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    Cool thing about using a stroke, is you can also adjust the stroke profile... see here for more unusual shapes.
    – Scott
    Commented Nov 20, 2019 at 22:28
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    @superluminal gradient stroke is a mech object ubder the hood. You can expand the stroke to a mesh. This allow you to do the symmetry flip.
    – joojaa
    Commented Nov 21, 2019 at 15:57

If you want to tinker you can try Illustrator's Blending:

enter image description here

The next cartoon shows how the arc is made:

enter image description here

  1. Start with the edge curves

  2. Make a three step blend to get 3 intermediate curves, expand the blend and ungroup the parts

  3. Convert the strokes to outlines to be able to make width variations with the direct selection tool. You can as well use path width tool, but then you must expand the appearance of the strokes to get filled outlines. If you try to blend non-uniform strokes in step 5 the result will be non-predictable.

  4. Change the fill colors of the areas to different greyshades. I used white in the 2nd and 4th shape.

  5. Blend the shapes, use stepping option Smooth Color.

What do you get with this hassle? If you use a gradient, you will get the result much faster, but the shading would be the same in every place. Subtle variations need masking or layered extra shapes.

Not asked: A couple of elementary extrusions in a 3D program can create in few minutes something which needs 2000% more effort in 2D drawing programs. One example:

enter image description here

3D program generates the shading and the perspective with zero effort. I drew only 3 circles, the centerline of the arc and an ellipse. I pulled each of the extrusions (the body of the lock, the arc and 2 holes) with two clicks.

The shown item has no photorealistic materials, it has got only 2 solid colors: grey and yellow.

The next example has some attempt towards photorealism altough there's still much to improve when compared to renderings from Blender or premium priced commercial 3D modelling packages (=no surface textures, coarse resolution, bad false border in the arc due non-continuous surface curvature)

enter image description here

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