HVAC: Adding Realism to Background Buildings

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Duration: 8:49

MRA Contributor Martin Tärnrot makes a flat background building look more realistic by adding weathering effects and a rooftop-mounted HVAC (Heating, Ventilation, Air Conditioning) system that he 3D prints. The building is a warehouse.


Before tackling the HVAC system, Martin adds grout between the tiles on the lower half of the warehouse building and some details on the upper part of the building. Then he paints the rooftop and assembles the HVAC system on top of it. This video is about working on the exterior of a building, though we have another video about adding interior realism to buildings in a layout.


On the front of the building, Martin uses white acrylic paint thinned with water and a bit of alcohol. Apply it with a wide flat brush. He uses the same wash on the upper part of the building to give it a bleached appearance and some variance in the blue color. The result of these weathering effects is the building front looks much more natural.


Advantages of 3D printing are super detail, ability to print many of them, and low cost. For this project, Martin used a resin printer and a drawing pack from Model Railroad 3D. Pour the resin into the printer, close the hood, press print, and about an hour later, the HVAC parts come out. Dry all the pieces and post cure them. Martin uses a machine for this, but you can also use sunlight.


Use a wooden stick with double-sided adhesive to simplify the painting. Martin secures each piece to the tape, then airbrushes them with a layer of gray paint and one of metal coating on top. Add a black wash to the pieces with ventilation bars for an added touch of realism.

Martin pre-assembles the ventilation duct pieces using fast-set glue before sticking them to the roof.

Here on MRA we also have more tips for personalizing layouts.

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