I built a couple of PRR FM flat cars. Part of the appeal to me of flat cars is their unique loads. When I learned that Model Tech Studio made this vertical engine kit available in S-scale, I bought one. The kit is also available in N-, HO-, and O-scale. It represents a vertical engine such as might be used by mills, factories, etc. for their electrical power generators. This photo shows the parts included in the kit. The instruction sheet is spartan, but sufficient. I wound up not using the thread and the wire shown near the bottom of the photo; they don't seem to match the S-scale kit parts.
The first thing I did was carefully remove the flash from the resin engine parts. It's not bad, but there's still some there. Using a knife and a small file, and some patience, it cleans up nicely. The carrier frame parts were glued to the paper/cardboard platform using yellow wood glue, very sparingly. I made sure that they leaned against a metal square to ensure their correct alignment.
I used Floquil Black to hand-paint the engine parts. After that had dried overnight, I used Folk Art Medium Grey acrylic paint to dry-brush the various edges as well as the manufacturer's lettering. This makes the part pop. I painted the flywheels with Polly Scale Rust. I then also dry-brushed the platform and frame parts, which were painted Polly Scale Reefer White beforehand. The dry-brushing made the frame look rusted and used (presumably when the engines were delivered, they were returned to the factory and re-used for the next customer). As you can see in the photo, I used a toothpick to make it easy to paint the flywheels.
I followed the photo Model Tech Studios has on their web site, which seems to have the rectangular part of the engine's top painted some kind of red color. I used Polly Scale Wisconsin Central Maroon for mine. The small-diameter wire the company provides for attaching the flywheels didn't make much sense, since the center holes in the flywheels are much bigger than the wire. I found a section of aluminum rod in my scrapbox that perfectly fit the inside diameter of that hole. I drilled a hole into the engine parts, as per the instructions, and then superglued the rod to the part. When that dried, I installed the flywheels. I had to bend them slightly on the shaft so that they appear in alignment with the engine part. I then used superglue to permanently fix the flywheels. After the glue dried, I cut off the rest of the exposed aluminum rod, and painted that area with the Rust color I used for the wheel.
Again, the instructions say to use the thin wire for the pole that goes in between the frames. I found a brass tube that matched the diameter of the frames' holes in my scrapbox, which I glued in place with superglue, and then painted with Floquil's Primer color. The instructions say to leave a bit of the tube exposed, which I did.
I attached the engine to the platform using Aleene's tacky glue. The kit comes with some string to be used as the part that is to simulate the tie-down of the engine to the frame. I don't think that's the right size for S-scale, so I decided to use Clover House's chain. I used part #384 which is 21-links per inch.
This photo shows the two vertical engines positioned on a PRR FM 40-foot flat car. There would be enough space for four of these engines on a 40-foot car.