When the player enters the workbench, an idle animation of the player's sprite is placed in front of it--without player control--to make it look like the player is actually standing at the workbench. (Check out the 'miniMAXIme' mod for important considerations on working with player sprites. Not everyone will be using the default player sprite.) If you want to go further, you could add a stool that hides the sprite's legs and switch from idle to running animations whenever the player is building something.

Cheers!