Volumetric light/God rays effect

As a guess, you'd need to start with a shadow box, to control the view.

You'd probably need to have a matched set of LEDs, one to make the back light as well as the front light.

Probably need a ton of potentiaometers and a lot of bradboarding before a lot of building.

Might could use some very short sections of fiberoptic to help give some "linearity" to the light for sourcing.

Maybe.

Perhaps.

We are talking about a technique largely used in photorealistic on-screen rendering rather than in 3D diorama making.

perhaps lighting some clear acrylic? if the edges are clear it will let the light in, and if the faces are diffuse (only the text in the image below is diffused), it will illuminate the face. This may give the look you want.

If you don’t mind a temporary effect for photography purposes, a multiple LED light source with selective angling of each LED could be combined with smoke from an e-cig, etc to provide something for the light to bounce off of.

I recall all those Hobby Japan magazine articles where a guy doing a diorama would take a rubber hose and blow into it after taking a suck on a cigarette to make either environmental effects or Godzilla’s firey atomic breath!

I’m not a smoker so I do not know if an e-cig would need to be sucked on to get the vapor or not.  Maybe I should ask that dumb 20-something kid I saw downtown, who was making all Mr Tough Guy using his e-cig - which was BUBBLEGUM flavored!

I’m old.  I don’t understand the current market demographic.  I gotta calm myself and lie down.  Oh wait, I have to mow the grass first.  Darned kids, get offa my lawn!