Using an LM-3S with the Accessory program loaded I've set up a Bachmann Spectrum Long Caboose (large scale) for dead rail control of the included lighting and to add some sound effects. This model has a highly detailed interior and electronics for an HO decoder for simple on/off control of the lighting. I wanted individual control and needed room for the LM, batteries, and speaker, so the stock electronics were removed including surgically removing the AA battery box interior to make room for a speaker. I'm still waiting for a small LiIon battery and speaker to arrive, but I have it fully functional using a larger LiIon pack and a too large speaker just hanging around in the interior for now. A full write-up with more photos is posted at
www.largescalecentral.com but here are a few highlight pictures and video of operation.
For the marker lamps I included a few non-prototypical functions just for fun - Flashing or alternating markers!
The stock board just before removal...

Wiring schematic...

Wired (less battery & speaker) and ready for operation...

Operational test...

Video of project program Version 1...
And video of using the Firebox lighting effect to simulate kerosene lanterns...
Not sure how to post video, so I'm just including links for now.
Mod edit: Embedded video links.