The Material Element Switcher track is a Sequencer track that you can use to animate Materials on an Actor. This enables you to change materials on an Actor by adding keys for specific materials on the track.
This tutorial uses a new Blueprint Third Person template project.
In the Content Browser under Content > Character > Mannequins > Meshes, drag the SKM_Manny or SKM_Quinn into the level.
From the Main Tool Bar click Cinematics and Add Level Sequence. Then open it from the Content Browser.
Add the Skeletal Mesh to Sequencer with the + Track button.
Under Skeletal Mesh Component, add a new Track and select a Material Element Switcher. You can find which material number corresponds to the element you want to change on the actor in the Skeletal Mesh animation Blueprint.
In the dropdown labeled None, select the first material for the sequence. Then, add a key for this material in the Sequencer.
Move the slider along the Timeline to where you want to change materials. Using the dropdown, select a new material, and add a new key to the sequence.
Repeat the previous step to add a third material.
Move the slider and add a key to change the material again. Repeat these steps as many times as needed.
Click Play to play in the editor. The playback of the sequence shows the materials change.