How do I make a Mesh Particle Emitter? (Legacy Particle System)

Mesh Particle Emitters are generally used when you need high control over where to emit particles.

For example, when you want to create a flaming sword:

Drag a mesh into the scene.
Remove the Mesh Renderer by right-clicking on the Mesh Renderer’s Inspector title bar and choose Remove Component.
Choose Mesh Particle Emitter from the Component->Effects->Legacy Particles menu.
Choose Particle Animator from the Component->Effects->Legacy Particles menu.
Choose Particle Renderer from the Component->Effects->Legacy Particles menu.

You should now see particles emitting from the mesh.

Play around with the values in the Mesh Particle Emitter.

Especially enable Interpolate Triangles in the Mesh Particle Emitter Inspector and set Min Normal Velocity and Max Normal Velocity to 1.

To customize the look of the particles that are emitted:

Choose Assets->Create->Material from the menu bar.
In the Material Inspector, select Particles->Additive from the shader drop-down.
Drag & drop a texture from the Project view onto the texture slot in the Material Inspector.
Drag the Material from the Project View onto the Particle System in the Scene View.

You should now see textured particles emitting from the mesh.

Unity Manual