From this answer:

Then there's the whole problem of parts which are simply not in production any longer, and for which the cost of reproducing them would offset the potential benefits of reissuing sets. (In other words, don't expect monorails to be reissued ever).

And this comment:

The cost for producing an old element again is presumably lower than the cost to develop a new element altogether, as long as the molds still exist (monorail parts molds are rumoured to have been destroyed, for example)

I'm getting the impression from these comments that there were issues with the monorail sets. What problems did they have? Were they too expensive to produce? Why would LEGO destroy their part molds? Why wouldn't they re-issue monorail sets?

3 Answers 3


For the molds: An injection mold is made for a specific injection molding machine. I very much doubt Lego is still using the same machines as they did 20 years ago. So to keep the molds, they would have to keep the old machines, including the service teams and infrastructure.

Also, machine parts are rarely made out of stainless steel, some old Lego ones clearly weren't. Stainless steel is just too bad at conducting heat, which is needed in an injection molding machine. In order to keep the molds for 20 years, they would have to keep them in shape, which means additional effort.

With regard to play value, and here it is becoming subjective, the monorail never added up. Monorail trains are only 4 wide structurally, while trains are 6 wide. Making monorail 6 wide would end up in a very unstable situation when manipulating the inside / load whatever. A robust, universal toy, they weren't.

  • 3
    Consiering how much LEGO vehicles have inflated recently, it's quite true that a 4-wide monorail would be very weird in a city setting.
    – Joubarc
    Mar 5, 2012 at 10:59

Since I'm responsible for both the answer and comment you point to, I don't have much more to say, although there is one capital element I feel I omitted: motors.

Track parts being just plastic, they wouldn't actually be that much of an issue to produce again. Maybe LEGO would need to make or even redesign some new molds, but if they felt there was a demand for it, that's probably not going to be the biggest issue.

However, motors and articulated bogies may be more of a problem, as they rely on non-plastic parts which may even be outsourced. Of course, this is by no means authoritative, but LEGO would have to come up with new motors, and presumably have them fit the newer PF system.

This is not impossible, and considering the PF battery box is only higher than the old 9V one, that wouldn't be much of an issue either.


Someone asked a LEGO representative at an event whether monorail would come back, and his answer was a quite clear "no plans to do so at the moment", citing difference in perception about it between adults and child.s Basically, only some adult fans want monorail, kids don't, so it would make little commercial sense to produce monorail again right now.

So technically, there would be some high costs, but no real impossibility. As far as I know, the old system was quite stable as well, so that's not an issue either. But what may be stopping LEGO is whether they feel it would sell or not - they aren't in the toy business to make losses after all. So presumably their first monorail sets didn't sell too well, or not enough regarding to their cost.

But in all honesty, we may probably never really know. LEGO employees will basically always answer "monorail is not coming back", but even they have only a limited vison of the future (and they can't tell about it anyway).

You may want to support some monorail projects on CUUSOO - who knows.


To repair and keep a Lego monorail system immortal - create Autocad files for parts. Translate each autocad file into a 3D printer file so you can re-create each part as they wear out. Later this year Staples will have 3d printers available along side the photocopier... so you won't need to buy a 3d printer to fix your monorail system.

For the electrical system, new components need to specs - mechanical dimension and electrical characteristics so they when they break they can be repaired to spec or replaced.

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