Build With Lego, K’nex, And 8 Other Toys At Once, With This Free Universal Adapter Set

This genius 3-D printed set will truly unleash kids’ creativity.

The Free Universal Construction Kit might be just about the best thing to happen to construction toys, like, ever. The 3-D-printable kit consists of adapter bricks that let you join parts from rival toys together. That is, you could stick a Lego brick onto a Lincoln Log or a K’Nex, opening up new horizons of imaginative awesomeness.


If you ever used toys like Lego as a kid, I’m pretty sure you tried to connect them up to any other construction toys you had around. We had a few Duplo pieces in our Lego universe (we called Duplo “Big Lego”), and they remained all but useless. Most kids, it seems, are similarly frustrated at this lack of interoperability:

Mostly, my parents got around the problem by never buying us anything but Lego, a common solution in the toy-starved 1970s. Today, though, we have 3-D printers.

Free Universal Construction Kit consists of 80 pieces that interconnect Lego, Duplo, Fischertechnik, Gears! Gears! Gears!, K’Nex, Krinkles (Bristle Blocks or Stickle Bricks), Lincoln Logs, Tinkertoys, Zome, and Zoob. Printed out and tossed into the toy box, these simple pieces let kids make anything they like, unlimited by the constraints of a single toy’s design. Do you want your Lego house to perch in a Krinkles tree, surrounded by a K’Nex fence? No problem. In fact, just looking at the adapter blocks themselves makes you want to start pressing them together, just to see what fits.

The kit is the creation of F.A.T. Lab and Sy-Lab, and is free to share and modify under a Creative Commons non-commercial license. It provides, say the makers, “a public service unmet—or unmeetable—by corporate interests.” You’ll need access to a 3-D printer to make the kit, but the files needed to print it are free to download

“Opening doors to new creative worlds is one major reason we created the Free Universal Construction Kit,” say the designers. “Another is that we believe expertise shouldn’t be disposable–and that children’s hard-won creative fluency with their toys shouldn’t become obsolete each Christmas.”


The idea is to make toys “forward compatible.” If little Peggy gets a new kind of construction toy this Christmas, then she just needs to print the pieces she needs to get it working with her existing toys. “The simple fact is that no toy company would ever make the Free Universal Construction Kit,” say the makers. “Instead, each construction toy wants (and indeed, pretends) to be your only playset.” With this kit, your kids do have one playset, but it is made up of all possible other playsets.

Because the designs are non-commercial, they sidestep copyright issues. You can’t take these 3-D printer plans and mass produce the new adapter bricks, but you can print them for your own use quite safely. “Even where a registered design is copied via a 3-D printer this would not be an infringement if it were done privately and for purposes which are not commercial,” says Simon Bradshaw in his paper The Intellectual Property Implications of Low-Cost 3D Printing.

Interestingly, all but two of the supported toys are no longer covered by patents. Zoob (patented 1996) and ZomeTool (patented 2002) still have active patents, so their adapters are being delayed–Zoob until next December (2016), and ZomeTool until November 2022.

Legal or not, that doesn’t matter in the privacy of your own home or playroom. This might be the best gift you could give to your kids this Christmas, so get hunting for a local 3-D print shop. Or better still, buy a 3-D printer as an early Christmas present to yourself.


About the author

Previously found writing at, Cult of Mac and Straight No filter.