Using a 3D model as a button, in Unity's UI system?

I have a 3D model, that is a child of a world space Canvas. How can I make it interactable, using the UI system? So far I’ve tried adding the button component, in addition to a box collider. I’ve also tried making it a child of a button prefab. No luck, am I missing something, or is it simply not possible, without using an event in a custom script?

2019 edit: Here’s what I ended up creating and using back in 2016/2017:

It has been tested in, and update for, 2019.1

You can use a UnityEvent to get the nice pretty editor event system just like a Button component.

using UnityEngine.Events;

[RequireComponent(typeof(Collider))] //A collider is needed to receive clicks
public class Interact : MonoBehaviour {

	public UnityEvent interactEvent;

	private void OnMouseDown() {

If you want to display 3D elements in the canvas combined with buttons, you can find a tutorial here.

You can use the OnMouseDown() function. Add it to your 3D model, and set the object child of the canvas.