Is it possible to render the object 'selection outline', or mimic it in some way, for a particle system?

Question

I am playing around with particle systems, and have been experimenting with this tutorial: https://www.youtube.com/watch?v=2bv973aqx-w

The system emitted particles from an icosphere, but the particle emitted is based on another object in the space. I'm basically trying to make it look nice. I think that when particles are next to each other, you cannot distinguish the shape, which I think doesn't look very good (Figure 1). When the particle system is selected, the objects all have outlines, which I think looks cool (Figure 2).

Is it possible to add an outline to a shape (i.e. every object in this particle system is based on an emission cube I have) which will then appear in the particle system. The main solution I've found online to getting object outlines is 'freestyle', which I don't think will work here as it is applied after, and therefore the cube generated in the particle system wouldn't pick it up.

Figure 1:

Figure 2:

Any solutions/workarounds welcome!

Answer 1

I agree, it's a very nice look.. It's easy to just get the wireframe of the cubes, but to capture all the edges created by intersecting faces without Freestyle is next to impossible in EEVEE or Cycles. There are some tricks you can pull with tightened-up AO, but none of them quite do it.

I think I would either shoot a pass in the Workbench renderer, say, displaying Object color of black, with Outline checked and set to white, to use as a mask in compositing later:

Or use the Header menu > View > Viewport Render Animation option to shoot the actual selection outline (perhaps with EEVEE,) bearing in mind you can create a custom theme under Edit > Preferences > Themes > 3D View, and change the Object Selected color:

If you would rather just have the wireframe, just say, and I / someone else will come up with a variety of ways to do that.