top of page

Building a 3.5' x 5.5' N Scale Layout Part 1: Benchwork and Base Scenery

Updated: Apr 2

Ok, so this new 3.5" by 5.5" foot N scale project layout you can see here features a double track, twice around design. The size of this layout is the absolute largest I can fit in the back of my vehicle, and so that was the size constraint limitation on this design.

The double track, twice around design is certainly track heavy, but allows for running longer trains, such as passenger trains, in a small space without having the train chase its tail so much. While there aren't a lot of switching options here, the layout does offer some operation, with effectively an interchange track at the top, a major warehouse to switch in the middle, and a team track on the bottom right serving a construction area. The tracks at the top and bottom right also serve as potential avenues for layout expansion, and I may go ahead and build a couple of small staging yards that can attach to both of those tracks. This way a train can enter from one track, take a loop or two around the layout, and then exit the other track. The two cross-overs also allow the left side of the layout to be used as a run-around track for switching operations as well if needed.

Download the AnyRail file: (right click and save the file, you won't be able to open it directly)

You can see the full list of track items used below. The minimum radius on the inner track is 12.4" and the minimum radius on the outer track is 13.7". Those radius curves are only on the inner loop on the left-hand side, half of which is in the mountain. The other curves all have radii ranging from 15 to 18.9" so passenger trains will look ok on these curves, and pretty much any available locomotive should run fine. Even the Athearn Big Boy, which I plan to pick up once it becomes available in a couple of months, only requires an 11" radius curve to run, so it should work fine on the outer track of this layout which has a 13.7" minimum radius.

Athearn Big Boy Preorder:


N Kato Unitrack 20000. Straight 9.76". 9

N Kato Unitrack 20001. Straight 9.76". (double plate track) 1

N Kato Unitrack 20010. Straight 7.32". 2

N Kato Unitrack 20040. Straight 2.44". 3

N Kato Unitrack 20042. Straight 2.44". (concrete) (double track) 1

N Kato Unitrack 20048. Buffer/Bumper Type C, 1.99". 4

N Kato Unitrack 20070. Straight 1.79". 3

N Kato Unitrack 20071. Straight 1.14". 2

N Kato Unitrack 20120. Curve radius 12.4", angle 45º 5

N Kato Unitrack 20121. Curve radius 12.4", angle 15º 1

N Kato Unitrack 20130. Curve radius 13.7", angle 30º 9

N Kato Unitrack 20132. Curve radius 13.7", angle 45º 1

N Kato Unitrack 20140. Curve radius 15", angle 30º 3

N Kato Unitrack 20150. Curve radius 28.27", angle 15º 1

N Kato Unitrack 20160. Curve radius 18.94", angle 15º 8

N Kato Unitrack 20181. Curve radius 15"+16.3", angle 45º (concrete) (double track) (superelevated) 2

N Kato Unitrack 20182L. Curved transition radius 15"+16.3", angle 22.5º (left) (concrete) (double track) 1

N Kato Unitrack 20182R. Curved transition radius 15"+16.3", angle 22.5º (right) (concrete) (double track) 1

N Kato Unitrack 20185. Curve radius 17.6"+18.9", angle 45º (concrete) (double track) (superelevated) 2

N Kato Unitrack 20186L. Curved transition radius 17.6"+18.9", angle 22.5º (left) (concrete) (double track) 1

N Kato Unitrack 20186R. Curved transition radius 17.6"+18.9", angle 22.5º (right) (concrete) (double track) 1

N Kato Unitrack 20202. Left turnout 7.32". (remote) 1

N Kato Unitrack 20203. Right turnout 7.32". (remote) 3

N Kato Unitrack 20210. Double crossover 12.2". 15º 1

N Kato Unitrack 20231. Right crossover 9.76". 1

N Kato Unitrack 20452. Straight 7.32". (bridge) (gray) 1

N Kato Unitrack 20457. Straight 7.32". (bridge) (gray) 2

N Kato Unitrack 20541. Curve radius 15"+16.3", angle 45º (viaduct) 2

N Kato Unijoiner 24818 22

N Kato Insulated Unijoiner (one package)

The layout will have a New England fall theme to it, so it will be fun to create lots of colorful deciduous trees for this layout. The structures indicated here are just placeholders and I'll be adjusting building placement once I actually pick up and build all the structures for the layout. The long structure in the front will be a passenger station, however.

Anyway, let's get on with the layout construction.

In terms of lumber, I used two pieces of 1x6 pine that were 66" long, five pieces of 1x6 pine that were 42" long, two sections of 1x3 pine that were 63" long, and four sections of 1x3 pine that were 42" long. For the legs, I used 4 screw-on and 4 butcher block legs that will be bolted on. The screw-on legs are so I can quickly put the legs on to work on the layout and then take them off when moving the layout out of the way during construction. The beefier butcher block legs are more for the final display of the layout.

I needed four brackets for the screw-on legs, a dozen or so 6" long 1/4" bolts with washers and nuts for the butcher block legs. 5" long bolts would have worked I think, but I had 6" bolts.

I also used one 4x8 sheet of 2" insulation foam board, one 4x8 sheet of 1" insulation board, and 1 4x8 sheet of half-inch insulation foam board. For assembly, I used lots of glue, wood screws, and nails, along with three cans of Great Stuff expanding spray foam, plus several pounds of Sculptamold. I have had comments in the past about wasting money with Sculptamold, but it is really cheap if you buy it in bulk. It is close to $4 a pound if you buy the small bags from craft stores, but it is closer to $1.75 a pound if you buy it in bulk from art supply dealers.

So, to assemble the frame I started with the end pieces. I glued and screwed on a 42" long section of 1x3 to the 42" long section of 1x6. For the other end, I used two pieces of pine to make up the 42" long section to make better use of my materials.

I then did the same for the long sides of the frame. Note that the 1x3s on the long sides needed to be 3" shorter than the 1x6 since the end frames on each side take up an extra 1.5".

Once I had all the sides done, it was time to assemble them. I added glue to another 42" long 1x6 and put that on one end as well, resting on top of the 1x3 inner portion of the frame. To keep things square I used some corner clamps. Then I drilled some pilot holes and screwed the 1x6 into the edge and sides. I also drilled a couple of pilot holes on each corner and used a couple of finish nails on each corner to further secure things while the glue dried. I put another 1x6 on the far end, then glued and nailed a third 42" section of 1x6 in the middle.

At this point, I took the mostly completed frame and test fit it in the back of my vehicle to make sure it would fit ok since it would be pretty frustrating to find out that the layout was an inch too long or wide to fit after it was completed.

Next, I took four heavy-duty top plates and attached those to each corner of the layout. Each of these is held on by five screws and a 28" long table leg can then be screwed into each plate, making for quick and easy legs. Again, I'll also be bolting on some stout butcher block legs later on, but these are great for quick setup and takedown of the layout during construction, or even afterward if you want to store it vertically.

The interior of the layout frame was to be filled in with a sheet of 2" insulation foam. This foam can be found in pink, blue, and yellow colors depending on where you buy it from. I had already rough-cut the 4x8 foot sheet to fit, and then I placed that on top of the layout in order to cut it to the exact size needed.

The utility knife with the heavy-duty 1" snap-off blades is a fantastic item to have on hand. The ones that have the smaller blades break too easily when cutting thick foam. I've only found the 1" version at Home Depot, but other places may have them as well.

Once I had the 2" foam cut, I put the half-inch foam on top and cut that one to size as well. The half-inch foam comes with a layer of plastic on the top and bottom faces, so be sure you pull that off before attempting to use the foam. The 1" and 2" foam boards do not have the plastic film.

I took off both layers of foam and then added glue on the 1x6 cross pieces. I decided I might as well add a couple more 1x3 cross pieces for added strength since I had them, so I glued those in as well before inserting the 2" foam board.

At this time I cut a hole in the center of one side for a Digitrax Loconet panel. This would have been easier with my jigsaw, but our other vehicle was blocking the cabinet I had the saw in. I didn't want to open the garage door and make the already cold garage another 20-30 degrees colder, so I drilled some holes in the side, then used a coping saw to cut out the rectangular opening. Pine cuts easily, so that wasn't very hard, but I did mark up the side a bit. I'll sand that out later, but for now, you can see how the panel fits.

I put the half-inch piece of foam back on the layout and then assembled all the track I had on hand for the layout. Some pieces still hadn't arrived in the mail yet, but this was enough to get everything marked out. Once the track was assembled I took a sharp to mark out where I wanted to cut the foam. Then I took my knife and cut the half-inch foam cookie-cutter style.

I started working on cutting supports for the half-inch foam out of other pieces of scrap foam. I got everything roughly to the right heights that I wanted, then worked on cutting supports more precisely.

To make risers, I cut off a block of one-inch foam, then using a ruler, cut progressively larger pieces off, using the previous piece as a guide. I ended up with a whole series of riser blocks to put under the half-inch foam base for the track. That way I could have a nice smooth grade to the track as it rose 2" from the front to the back of the layout. I arranged the blocks evenly and then added some weights to keep the foam weighted down. Then, I added some additional riser pieces to fill in any gaps of more than 4" or so. With all the blocks ready, I removed each block, added some glue, and then replaced it back where it was. I used a few long screws to help clamp all the foam pieces together. This way I wouldn't move anything out of place while working on the remainder of the layout. The backside of the layout was all one elevation, without grades, and the main center area was also going to be one elevation, making those sections easier to finish up. I glued and screwed those sections together, and I replaced the half-inch foam with a 1" piece of foam instead of adding another layer of half-inch inch foam to get that section to the needed height.

Once all my foam risers were in place I used some Great Stuff expanding foam to fill in all the gaps. I wanted to make sure the half-inch top layer of foam was fully supported everywhere. Adding the expanding foam adds a tremendous amount of strength, and it also is a great adhesive, binding everything together.

While the foam expanded and dried I patched all the dimples created by the screws with drywall patching plaster to create a nice smooth surface everywhere.

The expanding foam did need to be trimmed up in many areas, and then I needed to carve out the lake and river area. I tried hacking away at it with my hot wire cutter with moderate success. I eventually just went back to using my knife. I could have used my Stanley Surform tool, which would have worked great. However, with the very dry arctic air in place, static was already terrible, and I don't think I would have ever gotten all the little bits of foam off of me had I used the foam shaving tool.

To make the tunnel walls, I took some half-inch thick foam board and scored it multiple times to allow it to bend easier. I then cut the board to the needed height and tacked that in place with some nails. I did the same thing for a divider between the two tunnel sections, though that isn't really needed. But, this way if you look into each tunnel, you will just see the track in that tunnel and not the other loop of track. I also glued and nailed in that divider section.

So, you can see how things looked at that point. I also bolted on the large block legs at that point. I simply drilled a hole from each side of the corner through the side of the layout and the leg and put a bolt through each side.

Next, I cut some rough tunnel portals out of foam and attached those to both ends of each tunnel. I'll eventually add some real tunnel portals here, but this will help provide something to attach those future tunnel portals to, and will allow me to complete the inside of the tunnels. I did fill in some of the gaps with more spray foam and also added some additional blocks of foam and spray foam to the top of the tunnel section that you will see in a bit.

At this point, I mixed up a large batch of sculptamold to which I added some brown paint. That isn't needed but just provides a little tint to the mix so any sections that might chip off down the line at some point won't be a glaring white color.

I worked the sculptamold around much of the base of the layout, including to the inside of the tunnels. This will provide a nice rock texture to the tunnel walls and make them look more realistic if you peek inside the tunnels.

I continued to add more sculptamold all around the layout. I'll need to do more work on this later, but I wanted to get as much of this messier scenery work done as I could before I installed the track. This way I wouldn't have to worry about covering the track up or accidentally dropping a big glop of sculptamold onto a turnout or something I didn't cover.

That base layer of sculptamold really helps give a better sense of how things will eventually look. Once I put the track in place I had to make a few adjustments, the main one being to move a road over a bit so it wouldn't cross right over a turnout.

So, that brings us to the end of this post The benchwork is complete, along with a base layer of scenery. In the next video we will get the track installed, and all the track wiring complete, including hooking up a Digitrax DCC system, and wiring up the turnouts for remote operation. Then, we can get some trains running on this layout. So, watch for the next post and video in this series.

4,894 views0 comments

Recent Posts

See All


bottom of page