I | P | P.76 # Illuminate a Model Train

A few days ago I bought a toy for children in the supermarket while I 
was shopping. It is a small tram of the company Siku. Almost every child 
had cars from this company and somehow I still like trains very much. In 
the shop I spontaneously had the idea to light up this toy from the 
inside and so I decided to do this new project. I only describe the 
process here, which in the end really worked. In total I had four 
different attempts, but with the batteries it is really hard to work 
with. Why don't I use small square batteries? There are flat square ones 
for drones or racing cars, but no long rectangular ones. Like a little 
muesli bar. 

Most of the modern toy cars from Siku are made of metal and with these 
you can play and work well. But there are also many adults who collect 
the models. They are like the ones from Matchbox.  Some parts are made 
of plastic and at the time I bought the model, I didn't know if I could 
convert it at all. 

Before I start a project I examine the model completely and write down 
notes. For example, that the tiller on the right and left are made of 
metal. To save screws during production, the metal tiller is punched in 
to hold the plastic. Since I know a little bit about the production 
processes and design techniques of big toy companies, I could imagine 
that the metal tiller was hollow inside or maybe it was made of such a 
soft metal that I could drill it out.

Here I hold a drill head to the metal pin. An advantage of drilling was 
that the pin already had a small indentation and I could not slip off 
with the drill. As a first step I drilled out the punch so that I could 
remove the plastic. That was pretty easy and there were no further 

Here you can see the first individual parts. Underneath are the lower 
cover, the two joints to attach other small wagons and the two axles 
with the wheels. The axles are made of metal, which I think is pretty 

Under the first cover there is a second cover, in which the seats are 
also pressed in. This part is not black but a little bit grey, because 
it contains the interior of the tram.

Here you can see the plexiglass panes that were pressed out of a mould. 
This component is not glued but simply put on the two metal pins. 

Here I have photographed again the metal pin in detail. You can already 
see the slight hole I made a few minutes ago.

I then drilled out the indentation further and made the metal pin hollow 
from the inside. You have to be careful that the drill is sitting 
straight and not slanting. One should also drill very slowly. After 
drilling I rounded the edges a little bit with the metal file, so that I 
can cut my fingers while doing handicrafts. 

My idea was to drill out the metal tiller, then screw in a thread so 
that I could fix the plastic covers with small screws. This has the 
following reason. If you want to install batteries in a model, you also 
have to make sure that the batteries can be replaced when they are 
empty. This should be as easy as possible, so that a person who did not 
build the model can do it.  

This is where I insert the tap. A tap is unbelievably expensive, but in 
model making it is an incredibly good tool. You can make really 
professional modifications with it, which work with glue, but are not 
that good. Glue is always firm and can only be loosened with great 
difficulty. Screws can always be unscrewed easily, if you handle the 
internal thread carefully.

Here you can see the thread, which I screwed into the hole. You have to 
be very careful, because you can make mistakes very quickly. This is 
usually a problem when you work with such small models.

I always keep screws if they are left over from other projects. I 
collect them in small glasses. Since the model has a black cover, I also 
used a black screw. This is actually not necessary, but I pay attention 
to such small details. In my opinion it looks more professional when 
someone looks at it.

Here I put in a screw for testing and my plan worked. I am more than 
satisfied with the result and had expected much less at this point.

The next step of my plan was to add a small switch that I could operate 
with a toothpick or my finer nail. This switch should be located 
underneath the model and had to be as small as possible. In the hardware 
store I bought the smallest switch I could find. Actually I wanted to 
order it on the internet, but it was not worth the amount (10 pieces) 
and would have been too expensive. Also I can have a look at the parts 
in the shop, which I personally find better.

Here you can see the small metal tiller on the switch. In our project we 
will use only two of these pins.

To get the switch into the two lower covers we have to cut a small 
rectangular hole. I did that with a modelling knife, which worked quite 
well. It was exhausting and actually there must be a better solution for 

It is best to put the cover on a cutting mat so that it does not slip 
away too much or you will break your table. Please be careful, because 
at this point you can cut yourself shcnell into the funer. You need a 
lot of strength and patience to get the hole in the floor.

Here you can see the roughly cut out hole.

In order to make the hole in the floor tidier, I sanded it down with 
small files. It helps if you always fit the little switch into the mould 
to see where you still have to file. Also at this point you should take 
as much time as possible. 

Here I fitted the switch for testing into the first cover. It fits very 
well and does not take too much space. But I didn't know yet if it fits 
with the height, because the wheels of the tram are already very small.

In order to save time and to optimize my working process, I have 
pre-drilled small holes so that I can work better with the model knife. 
This worked very well and if you have a drill you should adopt this 
approach in your projects. 

The first time I tried to fix the switch with superglue, but it does not 
work. The switch is so small that the superglue also sticks to the 
switch and you can't operate it anymore. That's why it's better to 
always buy several components, so you don't get angry in the middle of 
the project because you don't have enough components. To fix the switch, 
I had the idea to use a piece of plastic as a holder. I took the plastic 
from an old disposable phone card, which you can easily cut with 

I used a phone card that was black on one side, so that it was not 
immediately visible inside the model. 

Here I'm just trying it out, whether it fits with the plastic and the 
switch. You should always do that before you glue something tight so you 
make fewer mistakes.

Here you can see the cover with the glued plastic. I very much like that 
there is a small slit on one side. There is a special reason for that, 
because the little metal pin of the switch has to go through it. You 
also have to pay attention to something like that. It always helps me 
when I make little sketches in a notebook and go through the next arebit 
step several times in my head. Better to think too much than to make a 

Here you can see the cover from the other side. This is later inside the 
model and you won't be able to see anything of the small plastic strip.

To prevent the switch from sliding away, I used thin double-sided tape. 
You can use that to attach the switch.

Here you can see the small tiller of the switch. We will need it later 
to solder the cables to it.

I had some problems with the battery. First I have to find such small 
batteries, which I could also install. I still had an old children's toy 
which I could take apart. These were three button batteries.

For lighting I decided to use an old piece of LED strips, which I had 
from another project P.59. 

Before you put any electrical circuitry into a model, you should always 
test it first. This will help to locate errors before reassembling the 
model. Unfortunately I had to learn this several times the hard way. I 
give you the advice to always do it this way, because it saves you a lot 
of trouble and work.

With this model I have refrained from drawing a real circuit. You can 
see the LED bar on the photo. On the right side is the minus pole and on 
the left side is the plus pole. On both poles cables are soldered. The 
minus cable leads from the minus pole to the three small batteries and 
then to another cable. The cable is soldered to the metal pin in the 
middle of the switch. Solder the cable to the left metal pin, which 
leads to the positive side of the LED. If you have a close look at it, 
it's pretty easy. 

So that I can glue the LED strip inside the model to the ceiling I had 
to take off a plastic part. I cut it to size and glued it to the roof of 
the tram with super glue after the conversion. Only a professional can 
see the difference and then you have to get very close to the model.


Here you can see the lED bar within the model. I used doppelseities tape 
to keep the strip under the ceiling. That was the easiest part.

I first clamped the model in a helping hand but that did not work very 
well. When soldering I simply put the model in the right position and 
held it with my little finger. This was unbelievably awkward but it 

Here I soldered the first cables. It was quite difficult and I had to 
buy a new soldering tip because mine was too big. That helped a lot even 
if the soldering tip was expensive. Sometimes you have to invest more 
money in tools to get better results. Never buy cheap tools. In most 
cases this is enough for a single project, but if you want to work 
professionally you will get to the point where you should buy reasonable 

These are the small metal plates, which are intended for the batteries. 
You probably know this from an old Gameboy. The metal spring pushes the 
batteries firmly into the battery compartment so that they don't fall 
out. In this model I did not use the spring and cut it off with a small 
side cutter. 

I fixed the three small batteries with electrician's tape, so that they 
don't slip. Then I glued the two contact plates. Do it in such a way 
that you get it off after a month, if you want to replace the batteries 
when they are empty.

As I had already noticed at the beginning of the project, I have already 
made some attempts how to connect the batteries to a circuit. Solder 
does not adhere to the surface and copper tape cannot be turned. Wire 
didn't work and a razor blade just cut me in the thumb. You just have to 
try and test a lot. You must not lose your patience and sometimes you 
have to leave the model there for a day until you have a better idea.

In the end, the idea that worked best was the one that was also the 
easiest to connect the batteries with tape. In this case I would have 
loved to have a 3D printer, because with this I could print a new cover 
for the interior. I'll keep that in mind for the future.

And here you can see the finished result. Unfortunately you can see the 
batteries and the cables but I couldn't do it better. Important was, 
that I managed to light up the interior. I will rebuild the model in a 
second version, but this time with better batteries and a 3D printer. 
With the LED strip and the component on the roof it worked great and I 
would build it like that again. All in all the project was a lot of fun, 
although I would have given up the whole project at one point, because I 
didn't see any solution. But I did not give up and continued to work on