I originally posted this build on the Atlas forum, back in 2012. I'm re-posting it here since I doubt many modelers visit the Atlas forum archive anymore. Someone might find this info useful, or maybe get inspired to build their own illuminated Sprinter.
It all started when I decided to buy a pair of BUSCH N scale Mercedes Sprinter models for my friend's layout. Specifically, the ones I found were painted for FedEx and DHL. While they were models of German prototypes, these vehicles are also widely used in USA, appearing as either Mercedes, or re-badged as Dodge. The same goes for the FedEx and DHL liveries - both are also often seen on US roads.
BUSCH8304.jpg
Me being me, I also wanted to illuminate their taillights and headlights. This task was made easier by the fact that BUSH used to sell these vehicles with built-in illumination consisting of a 12V light bulb and a plastic light conduit which directed the light to the taillights and headlights. The models I bought were sold as non-illuminated models, and while they are lacking the light bulb, they still include the light conduit.
But I did not like the idea of just installing an old-fashioned light bulb. I have pretty much converted to using LEDs. Then I also didn't like the idea of just installing a single large white LED where the light-bulb was supposed to be, because it would make it difficult to shield it and prevent the light from being visible through the windows and through the wheel-well openings. Instead, I decided to install 4 SMD LEDs: two red ones for the taillights, and two white ones for the headlights.
LightConduit01.jpg
I wanted to retain the structural shape of the light conduit (to make its re-installation easier). I started by gluing couple of pieces of 0.015" black styrene in the spots where I was planning to install the LEDs, then using a cutoff wheel in a Dremel tool to grind out areas where the LEDs will be installed. The added black styrene allows the light conduit to retain its shape even after the translucent part of it is ground out.
LEDs.jpg
I then soldered fine tinned bare wires to the LEDs. I used the SMD 0603 size LEDs. Pictured here are the white LEDs. I also used my custom mix of clear amber and clear red Tamiya acrylic paint to tint the LEDs so those cool white (bluish) LEDs produce a warm-white incandescent lights.
LightConduit02.jpg
I then glued the LEDs into the openings in the light conduit using a 5-minute epoxy glue. At the same time I also glued a piece of black styrene behind each LED to prevent the light from back feeding into the center section of the light conduit. That will make it easier to block any stray light from glowing inside of the model.
LightConduit03.jpg
I also etched a small circuit board to make wiring of the LEDs and resistors very easy and neat. That circuit board with current-limiting resistors was then glued to the light conduit, the LED wires were then soldered to the board along with the wires which will supply power to the model. The two front and two rear LEDs are wired in series, and each pair has its own current limiting resistor. This makes it easy to separately adjust the brightness of the front and the rear lights (the taillights should be much dimmer than the headlights).
LightConduit04.jpg
Next, I tested the LEDs. Then, I coated the tips of the the light conduit with liquid masking agent to prepare it for the next steps.
LightConduit05.jpg
The next step was to airbrush the tips of the light conduit white to maximize the light reflection.
LightConduit06.jpg
Last step was to airbrush the ends of the light conduits with black paint to prevent any light from being visible anywhere except at the ends of the light conduit. After each paint application I hooked up the power to check for light leaks. I ended up applying few layers of black paint to stop all the light leaks. I could have used silver paint, but I thought that black painted would be less visible (through the windows) inside the model.
LightConduit07.jpg
Finally, I installed the entire assembly in the shell of the model and placed dabs of epoxy to affix the conduit in place.
That took care of the lighting. But since I already had it apart I thought it would be fun to repaint it. I really like the FedEx Home Delivery paint scheme with a picture of a cute puppy carrying a package. So this project just got a bit more complicated. This means that I had to design and print a set of custom decals.
I found plenty of online photos of Dodge Sprinters in that livery, but then I got even luckier: I also found a vector-based artwork of the entire logo! I was originally going to trace the logo from one of the photos, but the vector version saved me several hours of work!
FedExHomeDecal.jpg
I designed the decal artwork in Corel Draw. In order to properly size my decals I place the models (on their side, front, and rear) on a scanner and I scan them at 600 dpi. That results in bitmaps which accurately represent the true size of the model. I import the scanned bitmaps into my drawing (onto a separate layer which I then lock). I then took the FedEx artwork and sized to the proper dimensions simply by placing it over the scanned images and manipulating it until it it was the correct size.
Then, since these models are of a Mercedes and I wanted to model a Dodge Sprinter, I also drew a Dodge-style grille to be applied over the filed down Mercedes grille. For the hood, I also created a black decal to simulating a vent at the base of the windshield. Here's a low-res image of the artwork. The colors look odd because it is optimized for my Alps printer. The actual printed decal will have the correct colors.
PlugMold.jpg
The reference photos I gathered show that the real FedEx Sprinters have blanked out windows in the rear doors (while the model has "glass" windows). To properly represent that I had to blank out the windows on the model. Since I'm planning on building more of these vehicles I decided to make master blank pieces, then resin-cast duplicates. To make the master blanks I covered the window openings from the inside with piece of masking tape. Then I applied some mold release agent to the window openings and I filled them with casting resin to be perfectly flush with the body. Once hardened, I popped the resin pieces out and I sanded the outside surface to be flat, then I glued them to a piece of acrylic sheet, and poured RTV mold of those masters.
WindowPlugs.jpg
I then cast several pairs and installed the blanks in the model.
Grille.jpg
At this time I also filed down the Mercedes grille so the Dodge grille decal could be applied after painting.
WheelSpacers.jpg
When I was reinstalling the wheels I discovered that the axles had too much side-play, so I glued pieces of 0.015" styrene to the wheel openings to restrict the side movement.
Next, I airbrushed the body with few coats of Tamiya Fine White Primer (decanted from a spray can). The yellow body needed few coats of primer to hide the yellow plastic. Then I airbrushed a couple of coats of white Accupaint. It dries semi-gloss: a perfect finish for applying decals. Next, I applied the decals and airbrushed the model with a semi-gloss Accupaint clear. I also hand-brushed black paint onto the door handles, and painted the front directionals and taillights. I first painted them with silver paint, then applied clear amber and clear red paints to simulate the colored lenses. Then the model was re-assembled. Oh, I also painted the wheel centers using a silver paint pen.
FrontLow.jpg
Rear_Low.jpg
Here's the finished model.
Coin.jpg
And the obligatory giant-coin photo.
FedExHomePhotoetch.jpg
Since I went this far, I also added few extra details: side-mirrors, and antenna over the windshield. The mirrors were photo-etched from 0.005" brass. Here's the artwork for the mirrors and for the LED circuit boards.
Mirrors.jpg
This photo shows the mirrors etchings(both, unpainted and painted). Before I painted them I applied some solder to the backs of the mirrors to give them a thicker, slightly dome-shape. The other side of the mirrors is flat and will be painted silver.
Mirror.jpg
And a closeup of the installed mirror. To me this small detail really adds to the realism of the model.
Antenna.jpg
Here's a closeup of the antenna. It's made from a piece of 0.0025" Nichrome wire glued in a hole drilled with #85 bit (smallest bit I own). It is pretty close to a thickness of a human hair.
SprinterMount.jpg
To attach this model to the layout (and to make sure it doesn't get sucked up into a vacuum cleaner during some layout-cleaning session) it will be mounted permanently using a brass tube. The wires to power the LEDs are routed inside the brass tube which is glued into a hole in the undercarriage. I will drill a hole in the layout's roadway and glue the brass tube into that hole. This way the model will be solidly attached to the layout. The visible part of the tube under the vehicle will be painted flat black, which will hide it from view.
Front_Lit.jpg
Rear_Lit.jpg
Finally, some night time shots.
This was a fun project, and I'm happy with the way it came out. So far I've built two of those models and I have parts for making more!
