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A Grand Unified Theory…of Toys? The free 3-D printable Universal Construction Kit at last allows you to combine your Lego bricks with K’Nex, Zome, Zoob, Lincoln Logs, Tinker Toys and Gears. The Universal Adapter Brick is like the ultimate Rosetta Stone of building, allowing you to think and build outside the box….
As a kid, there was nothing worse than building through my small collection of Lincoln Logs and realizing I was done for the day. My Pilgrim city would never expand into a major metropolis (a piece of...
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And Erector and Steel Tec sets? Oh, wait, just put a 1/4" hole somewhere on the toy. Problem solved. :-D
Tolerances are probably an issue, particularly for the tight fit of Lego.
You can go to and have them 3D printed at a reasonable price (for 3D printed parts). Choose the Durable Fine Plastic (green) for best tolerance, fine detail, and performance.
Tara Li
+Ashley Yakeley - They actually discuss that point. For the time being, home-brew RepRaps, and the like, probably are too loose to do perfectly, but that is expected to change over the next year or two. I think the RepRap folks are already looking at introducing multiple materials into their design.

The trick, I would think, to improving the RepRaps would be to use multiple runs of parts, and select only the ones closest to ideal dimensions, resulting in a more accurate and precise second generation, which could then be worked the same way to improve a third generation. I could be wrong on this, though.
Hang on, they completely overlook the American Plastic line of bricks, for which other manufacturers at the time made compatible stuff like working machine gears.

When I was a kid, I think the American Plastic standard was more common, but Lego was on its way to domination.
Are there resins which are considered non-toxic and toddler safe?
Rule 34... ;^) The Charles Stross book, of course... ;^)
Tara Li
+Derek Lichter - I'm sure there are. You'll just need to check the service bureau's websites to be sure.
Elsewhere, it was reported that there are hold-ups with the project because of patent/copyright issues.
Tara Li
+Nick Chapman - They discuss in the original announcement on their website that two of the systems are still under patents, and so while on the chart, the actual files aren't being released yet.
A hearty Free Universal Construction Kit to all these manufacturers!

(acronym cannot be accidental)
+Derek Lichter many 3D printers print directly in ABS, which is the same material as Lego and fairly childsafe.
It's easy to get around the precision problem, just glue on a sacrificial Lego block.
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