How to add border to the mesh in three js

I have a requirement where i have to stack the mesh one above the other.but the issue is I’m currently not able to differentiate between two boxes.
the boxes are created using

   var geometry = new THREE.BoxGeometry(  width, height, length );
   var material = new THREE.MeshBasicMaterial( { color: 'green'} );
   container = new THREE.Mesh( geometry, material ); = binname; 
   scene.add( container );

The current scenario is shown in the below img. The two boxes are stacked on each other but we cannot differentiate them.

Can someone help me with this.


Maybe to add edges to boxes: How to render geometry edges?

Thanks for the response.
I tried to implement the edge geometry and the edges are now visible but i cannot perform the drag operation correctly.
while performing drag operation I’m getting the below issue

I have created a fiddle for the same.
can you suggest me your to resolve this issue
the fiddle link :