[mg]

I don't have kids, but if I did, I would probably not go for Lego but for 3D-Printing.

It shouldn't be hard to print pieces that can snap together. In all kinds of colors and all kinds of forms.

I imagine the adventure of printing new pieces would be a fun thing for the kids and the parents. And when the kids are old enough, they can print pieces on their own. And a bit later design pieces on their own.

Would there be any downside to this approach?

[weli]

> It shouldn't be hard to print pieces that can snap together

I have some news for you. Lego piece tolerance is nuts. I think it is down to 2 micrometers. You can't achieve that in consumer 3d printers.

Now, you can make something that kinda works like lego but it wont have the structural integrity for advanced builds.

[bitexploder]

This. Even resin printers only get you kind of in the neighborhood of tolerance. Lego primarily uses injection molding for their parts. Their molds are insanely tight and low tolerance. One of the key costs of Lego bricks is the lifecycle of the molds. They don't last forever and lose tolerance over the course of several hundred thousand injections. Managing these molds and the sheer variety of parts they produce borders on logistical insanity. It is one of the most impressive logistics operations on the planet. I can build a functional car with fewer discrete pieces than large modern lego sets.

[rc5150]

Not only tolerance, but also the fact that fused deposition is just not as accurate/dense/strong as injection molding when it comes to the building-blocks application.

disclaimer: i'm not a materials scientist, just a tinkerer who 3D prints and wishes they had the capability to do injection molding.

[fsloth]

What you _can_ do is add slots for magnets. You can totally make "snap on" toys like this but it's a different concept.

[stravant]

You can easily print bricks that work. They will just require more force to assemble than normal because you have to make them slightly undersized to make up for the lower tolerance.

Just think of how many 3d prints you've seen that consist of multiple parts friction for together.

[everyday7732]

Printed pieces typically only have a single purpose, and lego-like snap together tolerances are hard to get working right with a 3d printer. Hell, they're hard to get right for the mass produced lego no-name duplicates. It can be fun to design shapes in tinkercad, but not as accessible for small children as just putting plastic bricks together.

[fsloth]

I actually think what you suggest _would_ be brilliant if there was a printer that printed as nice and detailed parts as Lego does from ABS. The digital ecosystem for that would be crazy.

But.

Modern consumer printers are way better than decade ago but they still sort of suck if you want any fine details.

"It shouldn't be hard to print pieces that can snap together."

It's actually quite hard to print pieces that are functional and look nice.

Modern consumer 3D printers sort of suck for small details still. If all you print are Lego Dublo sized parts. And print them from ABS. You might succeed _sometimes_.

PLA the cheapest default plastic for filaments for extruders loses fit quite fast (I've tried). So ball joints etc will get loose pretty soon.

"Would there be any downside to this approach?"

Well, the adventure currently is the printing part and it's mostly not fun but one of those activities masochistic engineers (like myself) take up as a hobby.

The consumer 3D printers are improving! Maybe one day. But the material physics are not that comforting there.

[deng]

Can confirm everything. PLA is completely unusable for this as it quickly deforms under constant pressure, so it is impossible to have a stable press fit with it. ABS would be the obvious choice (since Lego is ABS), but it's difficult to print. Generally, a press fit with ABS that can be handled by kids (so easy enough to create and remove), but still being sufficiently stable so that it can be handled, requires extremely tight tolerances which you will not be able to achieve with an FDM printer. Even very good FDM printers with small nozzles will have dozens of micrometers in tolerance, which is too large - pieces will either be almost impossible to fit, or they will just fall apart at the slightest movement. Resin printing is better, but again, the material is too soft and will not be able to withstand the pressures long-term. Even if you use special durable resin, it will deform quite quickly under constant pressure.

[woah]

Not to discourage you, but it sounds like you'd be getting into a nerdy programmer dad hobby instead of just giving your kids toys. I doubt your children would be interested in watching you for hundreds of hours while you learn to use 3d modeling software and debug printer feed speeds. And once they were old enough (10-13+) to appreciate technical slogs, why wouldn't they do something cooler like make actual robots instead of reproducing a toy that you can buy a much better version of for $10?

[dmonitor]

3D printing would be good at making figurines and such, but you can't easily replicate the Lego system's modularity without their high tolerances.

That being said, it should be feasible to make something that allows easily programming Arduino and raspberry pi to interact with legos, similar to how their Mindstorms line worked. That would be the best of both worlds.

[afavour]

There are off-brand budget Lego blocks available and they're (in my experience) all awful. Legos are very precisely manufactured to fit together smoothly, if the off-brand ones made in a factory can't replicate that then I don't have much hope for small-scale 3D printing.

[alexriddle]

The gap is reducing significantly - I have collected and built Lego for a long time and had this opinion but have recently discovered Lumibricks (formerly Funwhole) - excellent designs, and around 1/2 the price of Lego (but they all include lighting elements) and having put them together I can say they feel exactly like Lego. I believe there are other brands of similar quality.

[deng]

No sure what exactly you mean by "off-brand", but I have recently bought big sets from Mould King and Cada and they are perfectly fine. Not only are they cheap, I'd say the color consistency is even a bit better. The sets themselves are great, really creative, challenging to build even for older kids, something Lego stopped doing many years ago.