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I've been given the Christmas task of setting up an HO model train and rails around a child's room, so I researched a bit and found a shelf train would be the thing. So I go to measure the room in order to figure out how much wood I have to buy to make the the shelves (already thinking about how I'm going to make the round cuts for the inner edges with a simple hand saw...) when my measurements turn out to be: 314.5cm x 335.5cm x 339cm x 304cm... Yes, someone has been able to pull off this masterpiece of a room:

(Now, I'm not sure a bout the actual shape of the room, because as you can see, they had the delicacy of rounding the corners—to soften the magical skew effect, I guess—so it's impossible to measure angles. What I did was create lines in Photoshop with the lengths I took and simply found a way to
connect them so it feels right with what I'm actually seeing in the room.)
I guess my predicament is by now obvious: how on earth am I going to correctly measure and cut this shelf?!:

The mere thought of trying to find the correct angle for the corners and the correct radius is daunting! Not to mention the seeming impossibility of how to solve for the 2 corners where the angle will be obtuse and there'll be gaps between one side of the shelf and the wall!

Is this an impossible DIY project? What do you guys think? Am I perhaps going at it wrong and there might be a better, easier, (saner), way of going about it? Thanks in advance for your help!

P.S. The wood I'm looking to buy is particle board (the stuff that's used for melamine boards). I'm focusing on it more for its price, as it's much cheaper than pine or plywood (even MDF) where I live. But I'm not sure if it'll be the easiest to work with at the cutting stage.

UPDATE No 1

Wow! Thanks a lot for all your responses! There's a lot of very good info here that will help me approach this issue and perhaps will help others in the future!

One poster had a similar idea to a second, less elegant, but much more practical shelf layout I had also thought of:

I avoid the curved corner details and having to deal with them and, at the same time, make it more practical to fit together the whole setup without that much of a hassle due to the wonky, skewed construction of the room.

Don't pay attention to that red block floating around the top, it's just a leftover piece of shelving panel 😁. I virtually "cut" a large panel of 244x120 into 4 244x20 shelves and a larger 244x40 shelf that goes on top of the closet that's to one side of the room—yes, on the original design uploaded I didn't have the closet drawn in... that's another obstacle I've had to jump over... quite literally (more on that after). And I'm happy to see that I can get all the material I need from only one panel, which will save me some money.

Now, talking of the panel, why have I chosen particleboard and not plywood as a couple of you mentioned? Well, it's much more economic. I live in Spain and I know in other places plywood is dirt cheap but here it's 3 times more expensive than particleboard! I was surprised to find out—I'm not originally from here, so I too went straight for plywood as my first choice, only to find out that the "benchwork" would cost me much more than the actual train set and misc. models! In the end, I've decided to get a white melamine panel, the kind one uses to make normal shelves and/or a desk. It's still particleboard but has that melamine covering which gives it (a) a nicer finish that'll save me some work and (b) gives the particleboard a bit more resistance and makes it less prone to fall apart, I find. It only costs a couple Euro per sq. meter over the regular particleboard, so it's still way cheaper than the plywood.

To answer another particular a couple of you mentioned: I'm clearing all doors (there's 2—no windows) by placing the shelving flush agains the top of the doors' lintels and then going around the room at that height. It's not a small child's room, so the height isn't really forbidding; plus, she's tall, so she can manage. She really likes HO trans, and will be getting up close to her set when she wants to work on the model but, otherwise, it's more of a relaxing scene for her to see as she lies in bed, especially at night, and falls asleep with the sound of the train rolling by. Now, as I mentioned, the closet is another big obstacle, as it stands 9cm taller than the lintels, so I can either raise the entire shelving a further 9cm (which I'd rather not, as it does start to become more of a ceiling train) or I can have inclines going up to and down from the shelf on top of the closet. I'm thinking of putting 50mm pink foam on top of all the shelves except the one on the closet; which would help me make it so that the incline that has to go up and down from the lower shelves to the top of the closet would only have to reach up 4cm, which would mean I can get a good 1 in 30 incline starting at 120cm from the closet (perhaps a little diagram will help better show what I'm talking about exactly):

I understand a 1 in 30 incline is about the bottom margin recommended for an HO gauge train set, as it's already a 3.33% incline, which is way more than any prototype rail actually has. Because we're talking about a passenger train, with a rather strong British Gresley A1 locomotive and 3-4 pullman cars, I think there'll be no problem getting up and down this slope. Now, I've read somewhere that a 1 in 30 incline is really not ideal (aesthetically speaking) for a model main line. I personally don't see that but perhaps do understand there might be a lack of realism. All-in-all, if you can't get up to 1 in 60, which seems to be the best ratio, 1 in 50 is a preferred incline for serious modellers and, indeed, I could even get it up to that:

I don't mind it visually. It may even be interesting to create some sort of mountain side view for the inclines. What do you guys think? I guess I'll know for sure once I get the tracks in place and do a test run with the loco.

As I said before, I could just raise the entire shelving and have it flush with that on top of the closet. If I connect all the shelving (including the one on top of the closet) then I'd be raising the entire set 9cm and I could also put some foam on top of the shelf on the closet. If, however, I just raise the outer shelves enough to get the foam flush with the shelf on the closet (and don't put foam on that) I only have to raise the thing up 4cm. Now, 4cm higher or lower doesn't seem like much and perhaps is not worth the hassle of having to make inclines... I don't know. 9cm already seems like something considerable, but perhaps in the end, visually, it's all the same... What would you guys do?

Another thing I'm planning on doing is running the rails rather close to the edge, because it'd be a shame to push them back and have the train be half-hidden all the time. So I'm going to pop in some wooden posts at intervals on the very edge and string them through with some sort of thin wire or string to make a barrier in case of derailments that will look like some rural fencing. Any ideas how high I should make them to insure nothing rolls off the edge, especially the loco? I'm thinking that some 3-5cm should do the trick...

Finally, the last obstacle I'll face is the wiring. The rails are easy enough to wire but we're also thinking of modelling a little town on the closet, and a little village on one of the corners, perhaps a farm or something like that on the other, so we're also going to need to wire some lights, at the very least—perhaps even some other mechanical stuff. I'm guessing what I'll have to do is cut surface strips on the actual foam and have the wiring go under there. In the case of the closet top, which most likely will have no foam, I'm probably have wires run across the surface and then I'll hide them putting some scenery on top. Any other ideas?

This all is perhaps not the best solution, but I think it's what I'll end up going with. Still, as I work my way into the project I'll know for sure. Which is why I'm not marking any answers or posting these "final" plans as an answer, because I may very well change them upon finding a better solution, or someone else might give me another recommendation here, and then my plans and final result will change.

UPDATE No 2

I realised quite a lot of you are worrying I may be in for a couple of bad surprises.

The first, and perhaps more worrisome: that once I work all of this out I'll realise the HO train set's rails just don't fit what I've made!

Well, don't worry about that. I have taken this into account, which is why I need those rounded or diagonal corners. The first thing I did was use AnyRail to build up the basic track layout with the parts I'm getting in the set I bought, to see what other pieces of track I need to buy and, of course, to see if the room could hold a nice and viable shape. This is my current track laid over the room and shelving diagram:

In the diagram it fits almost exactly in some parts, which gives me some confidence, as that means I'll be able to make it fit even better by working a little with the track.

The set comes with a basic Hornby oval plus a basic extension pack:

• 8x R607 Curve radius 43.8cm, 45º


• 1x R612 Left turnout 16.8cm


• 1x R604 Curve radius 37.1cm, 22.5º


• 3x R600 Straight 16.8cm


• 2x R601 Straight 33.5cm

and I decided what would be more practical and economical would be to add

• 7x R621 Flex track 97cm

to complete the layout I show. First, because the flex track will allow me to make a skewed quadrangular track that follows in the Tim Burton-y spirit of the room's architect (+1 for the person who said I should find the guy and shake him into his senses). Then, it's also cheaper than buying straights, and as I would have to at least buy 1 piece of flex track in order to fill in gaps that'll surely come up, I might as well just buy them all flex and enjoy the extra latitude they offer.

About the second worry: realising too late that the "straight" walls aren't really straight... well, I thought of that too! Because no home improvement work in this house has been made at all easy by the marvellous architects who dreamed it up! However, I can happily say that whoever built the room wasn't that out of their minds! Of course, they aren't the straighest walls in the world, but they're straight enough. What worries me more is that the floor and ceiling aren't perfectly balanced either... What can I say: Europe's building codes are different... and old buildings with wonky architecture are fine (I once stayed at an AirBnb apartment building in France that was entirely off kilter by several degrees! So much so that when you walked in the apartment you had to hold on to the walls as you felt you were going to fall over. And objects left on one corner of the room would slide down slope to the other!). Anyway, so if you measure from the floor up or the ceiling down in any two points and set your horizontal shelves according to those measurements you'll find that they're very obviously tilted to one or the other side! So I'm looking forward to that part of the adventure! (Luckily, my iPhone has a rather accurate level I can use to get me out of that mess.)

Anyway, again, thanks a million for all your input!

The Easy Way

Fortunately, you're holding up a model train, not an actual train, so you can take some liberties.

The hard part is following the rounded, off-square corners; the easy way to work around that is to literally cut corners. Rather than attempt to follow the rounded corners, just install four shelves as long as the straight parts of each wall, then measure and cut four trapezoid shaped connectors for the corners. Just about any method would work to join the trapezoids to the main shelves since there's not much weight to support. You might use pocket screws, maybe half lap joints if you have the router etc. available.

The Hard Way

You could do some geometry, measure diagonals, get out a protractor, etc. etc., and find the angles. You may even be able to use an app that works with your phone to determine the layout. But in my experience these things don't end well :)

Here's how I picture doing it ... be warned, these things don't always work the way I pictured it.

Install your shelf brackets first

You'll want to rest the shelves on the brackets as you figure things out. I'd place them all on the straight (not rounded) part of the wall, but try to get one as close as possible to the point where the wall starts to round.

Make each shelf as if it was going to be the only shelf

This will be the most time consuming step.

Use a contour gauge, make a pattern out of cardboard, and cut each shelf to hug the rounded part with a jigsaw or coping saw. A rasp may be handy for fine adjustments. Be prepared to spend some time and possibly waste some material.

Err towards removing less material and you'll be less likely to have to scrap it and start over. Remember that a 5-6mm gap will be fine, you're not machining an engine block, you don't need thousandths of an inch precision.

Look forward to the steps where these shelves are cut to fit - don't waste time fussing with a good fit in the portion that's going to wind up cut off.

Lay the shelves in place and mark intersection points

This step is easy but it's the key to the layout. Lay the North and South shelves in place on the brackets, then lay the East and West shelves on top of them. Mark the inside intersection points in each corner, on both shelves.

Cut the East and West shelves

The exact angle isn't important, you don't have to bisect the angle perfectly as long as you start the cut from the intersection point. That will be the key to making these fit nicely.

Mark and cut the North and South Shelves

Now you're coasting... put the East and West shelves back on top of the North and South shelves and mark the cut lines.

Check the fit, and fasten the shelves to the brackets, and you're ready to put tracks on it.

You don't. You transfer cut marks.

You don't need to make a paper plan of your cuts. Just lay the shelves on each wall.

Don't attempt to span a whole wall with 1 shelf board, it should always be 2 boards for ease of handling. If the wall angle is less than 90 degrees, initially cut each shelf at 80 degrees so its back can go all the way into the corner. The shelves will overlap at the corner.

Now see where the shelf fronts (lips) meet. From that point to the actual wall corner on the upper board, snap a line. Pull that board, cut on that line, and reinstall it. Trace (transfer) that cut line onto the lower shelf. Take the lower shelf off, cut on that line, and reinstall it. They should fit within a pencil's width of snug. You really don't want it snug snug. 5mm of gap is better than 0.

You don't want to fit it too perfectly, or ordinary expansion/contraction could jack against your walls and do damage.

When you get to the corners, figure out the radius that your train will need. It's the same trick, clamp up the piece and then transfer the cut marks from the pieces it needs to attach to.

Just four simple cuts.

I would use slightly oversized brackets and leave a gap against the wall. It might actually make for a nice floating effect.

Set a shelf along one wall, leaving a uniform inch or so behind and keeping all shelf boards in alignment with each other. Leave gaps at the ends, also. Now lay the shelving on an adjacent wall, overlapping slightly with the first. Trace the first shelf onto the second and cut to that angle. Rinse and repeat twice more.

You'll end up with well-fitted corner joints and avoid the whole wavy wall, rounded corners debacle altogether. The best part? Just four simple cuts*.

12 or 16" pre-finished or melamine particle board shelving would probably work just fine for this technique, assuming supports every 32". All cut edges would be hidden. Make your cuts from the visible side (top or bottom, depending on shelf height) because the tearout side won't have as clean an edge.

_{*I realize that additional rough cuts may be necessary to fit the shelving for tracing. The four cuts statement refers to finish cuts--those required to make everything work together and look nice.}

I'd suggest going with the plywood over the particle board. Will probably be a lot lighter, and probably more dimensionally stable as well. Depending on your scenery goals, I might suggest using 1/2" ply with a foam top to allow ground contours for visual interest. Use blue or pink foam, and not the white beaded foam, as that is much more messy. To cut the foam, use a florist's hot knife, though make sure to have suitable ventilation.

If you have at least a power miter saw, I might suggest doing the corners in pie-type trapezoidal segments like I have done on my layout, and then gluing the corners together with the top layer offset from the bottom layer by 50% for gluing surface. Such as this:

It looks like your current diagram is to have it all the way around the room. How about windows, closets, or doors? Those need to be accounted for in your plans, along with anything else. If you're planning on a high-level run (i.e. close to the ceiling, above any doors or windows), HO is not the gauge to do it in, as it will be too far away for easy viewing by children.

Is the target audience (i.e. child) already a train fan? If not, you may be going for a whole lot of extra work that will never be appreciated nor used enough to justify the cost and time you'll be spending. If this is the case, then I would suggest setting up a 4x8 foot sheet of plywood on some crates or legs and doing some loops of track at child level so they can interact with the train.

From personal experience, a child needs to be able to interact with the train to be able to keep their interest, and don't skimp on quality of the train, as a poorly performing train layout is not going to keep the child's interest for long at all.