An Emerging Symbiosis

January 4, 2013

I’ve read plenty of articles that boil down to, “What is LEGO going to do in The Future, when anyone, ANYONE! can print their own LEGO kit in their basement?”

One can swap LEGO with whatever $manufacturer you choose: Tinkertoys, Lincoln Logs, K’Nex, Colt Firearms. (The 3D printing of firearms is a topic I’ll visit sometime soon, but for now let’s stick to things you can buy at Toys R’ Us.)

The implication of these articles is often that $manufacturer is ultimately screwed. Sooner or later, The Future will arrive and $manufacturer‘s revenue stream will dry up as we all print their products willy-nilly in our living rooms.

I see things differently.

This afternoon my son was playing with the new K’Nex set graciously provided by Grandpa and Grandma. He couldn’t find the one gray piece he needs to finish his roller coaster, so I volunteered to print him one.

Thingiverse doesn’t have the specific piece I need. Nor should they; K’Nex owns the rights to their designs and they deserve to profit from them. They’ve invested the capital in building their factories and hiring designers, and it’s their right to enjoy the fruits of their efforts. Thingiverse probably doesn’t want or need the legal headaches associated with hosting knockoff models of popular toys.

(I just realized I’m making arguments similar to those made by drug companies. Maybe there’s a path to The Future where designs go “generic” after a couple of years so that $manufacturer has an incentive to continue creating new ones? I digress.)

So Thingiverse doesn’t have the piece I need, but they do have pieces from the Universal Construction Kit, which lets one link toys that weren’t designed to be linked– Tinkertoys to Lincoln Logs, Duplo to K’Nex, and so on.

So I grabbed a K’nex -> Duplo connector, did a little vertex surgery, and now I have the piece I need as a 3D model.


To print!

This is what I got, printed in red ABS. Note the difference between my bootleg copy and the original. Cue sad trombone.


You could argue that the MakerBot Replicator is *the* top-of-the-line home 3D printer. There are others in its price range that have more or less the same capability, and if you go an order of magnitude more expensive you can get yourself a small industrial quality prototyper with superior resolution.

Part of this failure is surely inability to configure my printer settings properly, but I think a larger part of it is that the Replicator just can’t print this precisely yet. K’Nex parts are cast in ABS, which effectively means they’ve got molecular-level resolution. No way I can get that on my desktop in 2013.

A further limitation of the additive printing process is those overhangs– even if I could get the resolution right, gravity would pull those long grooves down and make the part significantly less K’Nex-able.

You might get around this by printing the entire piece as a column, but my experience in printing toothpicks vertically is that they tend to fail.

So K’Nex gets a pass until the resolution of home 3D printers increases. Maybe the Form1 will be able to do it. We’ll have to wait until the Form1 is out in the wild to see. I’m hopeful, because right now a lot of my ideas are limited by resolution and gravity.

What about lower-resolution objects, like Tinkertoys? Tinkertoys are well-within the resolution range of the Replicator. I’ve already made a couple of Tinkertoy-compatible items.


There’s nothing stopping me from printing a Tinkertoy clone right now except time, but the manufacturing process that makes Tinkertoys at gets them to the toy store (or, in my case, Amazon) is so much more efficient than a Replicator that it just doesn’t make sense, it can’t *ever* make financial sense to print these toys at home unless the price of plastic feedstock drops to near zero.

(Ultra-low-cost feedstock might happen with a descendant of the Filabot Reclaimer, but it’s not here now.)

So I don’t see home fabrication of toys taking off anytime soon, but here’s what is happening. People are using their 3D printers to extend the capabilities of their existing toys.

gears This is the emerging symbiosis: traditional manufacturing is now and likely will forever provide the base of the mass-market toy experience, cranking out LEGO bricks and Lincoln Logs by the millions. Home-based 3D printers will make small production runs for niche items– gears that extend your Tinkertoys, wacky Lincoln Logs accessories, and the like. Over time, $manufacturer will adapt to the proliferation of high-resolution home printers by offering certified premium models, guaranteed to be interoperable with their mass-manufactured cousins.

zheng3_penny_catapultIn short, I think 3D printers aren’t going to kill the toy industry, they’re going to make it much more creative. And haven’t even mentioned new toys like Dutchmogul’s Pocket Tactics, or my pet project, Seej.

Seej bloxen, Ransom

December 27, 2012

I put this model on Thingiverse a couple of days ago but forgot to put it up on the blog. This is a hollow bloxen for Seej with an articulating door. Players place small wager items inside their own ransom bloxen. Winner takes all.


Some of the Ransom Bloxen’s design DNA comes from this dice plinth, in particular the flagstones on the base.


I’ve carved out geometry for an articulating door hinge, but the Replicator’s resolution is too low for it to print; we’re in the sub-millimeter range here. Note that the tiny (and skeuomorphic) rivets print just fine though.

Casting about for new ideas.

October 1, 2012

I’ve been using my MakerBot to make things to make other things, and here’s my first effort: sidewalk chalk molds in the shape of Seej bloxen. Casting with plaster is a lot of sloppy fun, especially for the under-12 set.

I’m not an expert caster, but here’s what I’ve come up with to get a consistent product out of this mold.

First, liberally smear all interior surfaces of the mold with a lubricant of your choice. I used petroleum jelly, but I imagine anything greasy would work: Murphy Oil Soap, a little EVOO, liposuction byproducts, whatever you have around your workspace. This will help you remove the finished product from the mold at the end of the process.

Mix the plaster and water according to the instructions on the package, generally about 2 parts plaster to one part water. Add a little pigment and mix well. Let the plaster sit for a minute or two once it’s mixed.

Snap the two halves of the mold together and fill it about 2/3 full with plaster. Tap the mold on your work surface a few times to remove air bubbles and make sure it gets into all the corners. Fill the mold up to the bottom of the mortises, and gently insert the tenons.

A little bit of plaster will bloop out. Wipe it off, tap tap tap the mold on the work surface, and then elastic band it together.

If you’re not using any pigment, let the mold sit for about 45 minutes before removing it. If you’ve mixed some powdered paint into the plaster, let things sit for at least 90 minutes. Four hours is too much, it’ll make the bloxen difficult to get out of the mold.

While you’re waiting, call your grandma. She misses you, and you never use all your minutes anyway.

Remove the base of the mold first, and then one side. It might help to gently wedge the mold apart with a screwdriver or chisel.

Getting the bloxen out of the second half of the mold can be a little tough. I recommend tapping the mold smartly on your work surface a few times and then wiggling the block out. Putting the mortises back into the plaster bloxen might give you some leverage, too.

Then let the bloxen rest until you’re ready to use it. A day or so of resting will give you a dandy piece of sidewalk chalk.

Using the finished products for their intended purpose might mean you have to go outside for a few minutes. May cause interaction with small children, who have germs.

Temporarily discontinue use of vitamin D supplements if you frequently leave the house for extended periods of time.

Download these models for free from Thingiverse.

Seej in Education

September 27, 2012

Here’s a couple of photos of a Skype call I did with a Colorado high school Engineering class this afternoon. These students are designing and 3d printing engines of war for use in an in-class Seej tournament, date to be determined.

I’m the tiny pale dude trapped inside the MacBook Pro.

This looks like a clever band of rogues– I’m looking forward to seeing what designs they come up with. We chatted about 3d design for about half an hour and bounced some ideas around. The conversation really picked up when I suggested someone design and field a robot flamethrower.

Won’t someone please design an Open Source robot flamethrower?

More pix as I get ’em. These students are your engineering future, world. And they can’t wait to blow some stuff up.

Welcome students!

September 20, 2012

The flashing bank of indicator lights on this blog’s control panel just started going crazy, which means that we’ve got another Seej tournament on our hands, somewhere in the world.

If you’re an engineering student and you’ve got a Seej-related assignment, welcome! I’ll be happy to help in any way I can. Ask questions in the comments below, or email me privately at if you want to keep your opponents from discovering your nefarious plans.

Or find me on Twitter, I’m @Zheng3_Jim.

Seej Pillar

August 30, 2012

My Seej fortifications have been looking a little mundane lately so I designed this seven-piece fluted column to add a little bit of architectural elegance to my battles. It handily interlocks with existing Seej bloxen, and collapses spectacularly when hit with a penny from a Seej engine.

It’s pictured here with a Riveted Bloxen for scale.

This post was originally going to be about how to adjust your gCode by hand-tweaking it to get a good raftless PLA print, but then I went ahead and downloaded ReplicatorG 037. Editing gCode wasn’t necessary, except to set the HBP temperature to 65°.

Perfect print the first time out, even with a relatively complicated model like this one. No hocus-pocus required.

1.75mm Blue PLA (available at Amazon)
Infill 10%
Layer Height .20mm
Shells: 1
Feedrate 25mm/s
Travel Feedrate 55mm/s
Print Temperature 190°
HBP Temperature: 65°

Download the STL from Thingiverse.

Key fail.

August 27, 2012

This is a failure of a winding key from a Penny Catapult.