Shapeways 120-cell

[jducoeur]

It occurs to me that I haven't posted a followup to my previous post about Shapeways yet.

So I did wind up ordering a couple of things there, experimentally -- that proved educational. I ordered two items, both from the catalog of a creator named "Bathsheba", who specializes in using Shapeways to print fancy 3D mathematical objects.

The first was The 120-Cell, which I got in the "Winter Red Strong and Flexible" plastic. That was really too expensive a toy ($85), but is quite a cool demonstration of the power of this technology. The thing is essentially a 3D projection of a 4D hyper-dodecahedron. It's simply a frame of a shape, but so ridiculously complicated that making it using more conventional technologies would be a real pain in the ass. The thing came in with no problems, though -- a bright red, preposterously overcomplex bit of plastic about four inches across. The "Strong and Flexible" plastic seems to live up to its billing, putting up with moderate abuse despite the relatively fine struts throughout. It's become my new fidget toy at work, because it is great for simply flipping hand-to-hand while I think or listen in meetings.

On the downside, the second toy was the "Triple Torus Pendant" -- which doesn't have a link any more, because it demonstrated a flaw in their system. This thing was a beautiful gold-plated stainless steel pendant, with two identical interlocking elements. As it turns out, freely-moving pieces are forbidden for stainless steel, but they apparently didn't figure that out until I ordered it. Far as I can tell, Bathsheba didn't even know that the item was illegal until I tried to order it and they went to print one. So now I have a store credit that I need to think about. (They offered a refund, but it's fairly inconvenient, so I probably will buy something else instead.)

Overall, the process went pretty smoothly other than that. It's a bit slow, but they kept me updated along the way. Someone expressed concerns about shipping, but that seems to now be factored into the price of the items.

It's definitely still a tad too expensive for regular use, and they need to file off the edges of their process. But I'm generally encouraged, and starting to think about, eg, how I might use Shapeways to create the occasional truly esoteric LARP prop. It's cool enough that they print in plastic, but the idea of being able to print in glass, stainless steel, and even sterling silver -- it does raise all kinds of intriguing possibilities, and I find myself pondering the notion of *printing* one of the key items in Girl Genius that was simply an item card the first time around...

Comments

[handymonkey]

I was just looking at this, and thinking of the game of Astrological Tables a couple weeks ago, and thinking "properly balanced 7-sided dice..."

[jducoeur]

Someone would have to do some fairly interesting physics calculations to come up with a good definition of "balanced". But yes, I'm sure you could do much better than my hand-made sculpy ones...

[etherial.livejournal.com]

Chessex makes 5- and 7-siders. I hadn't gotten around to doing the math on mine before they were stolen, so I have no idea if they were fair.

dNs are trivial if you're willing to use Crystal Dice.

[keshwyn]

...you play Earthdawn. :)

[etherial.livejournal.com]

Wednesday is Earthdawn at Camelot.

[keshwyn]

Wednesday is stupid afterhours concall at work. :/ I think you got the better deal. (Which edition?)

[etherial.livejournal.com]

Started the current campaign with Second and will finish it out that way )though one player wanted to become a Traveled Scholar midgame, so I told him to just use the 3rd ed. rules rather than update it myself). Will probably switch to 3rd ed. when we have time to sit down and go through the books and fix them.

I *think* I know who you are, but am now rather intrigued...

[keshwyn]

Nora. If I'm remembering correctly, you let me and mindways store our archery equipment in your tent at Pennsic last summer so we wouldn't have to keep trekking back to E18. (And thank you again!)

[jducoeur]

Oh, sure -- I mean, the period solution is to use simple log dice, which can easily be fair. (Indeed, I was very disappointed to discover that the *description* clearly says that log dice are preferred, even though the *image* I was working from shows both.)

But the challenge is making a pentagonal-prism die (like the ones I use) that is solidly fair. Mine work well enough to not be a problem (actually surprisingly well for a hand-made guess), but I'm under no illusions that they'd hold up statistically...

[fairdice.livejournal.com]

You called?

There are commercially-available 5- and 7-sided dice, the best of which is designed by Lou Zocchi:



These dice aren't "fair by symmetry", like the ones you usually use, but you could argue that there is some die of more-or-less this shape that is "fair by continuity" — that is, if you made something like the 7-sided die that's very flat, it would always land on one of the pentagonal sides, while if you made it really tall, it would always land on one of the rectangles, so somewhere in between must be a fair one.

But figuring out where by physics is an awful idea :-). Instead, Zocchi worked with engineers and build a die-rolling robot, then cut and rolled dice with thicknesses in increments of 1mm, rolling each die some 10,000 times, if I recall correctly, and then interpolating the curve to find out the "fair" thickness.

But because it's not "fair by symmetry", this extreme precision is a little unwarranted: if you're rolling your die onto 10mm-thick plexiglass, as the robot did, then the die really is fair. But if you're rolling it onto something that's bouncier or harder (or sticky or slanted or underwater or on the moon or...), then the fair thickness would be different.

Of course, you can always buy a d14 and number it appropriately...

[jducoeur]

... the statistical approach hadn't even occurred to me. Does make lots of sense, though.

(And I actually have a set of what I believe are his 7-sided dice around here somewhere. I was very amused to find them and discover that they had the same solution I'd come up with, to put the pips on the edges -- which is specifically *not* what the period source says, sadly...)

[dkapell.livejournal.com]

I've also looked at ponoko.com, which does laser cutting, as well as 3d printing, in many materials. Refreshingly, they each seem to both have blog entries about how cool the other one is. I may be printing/cutting some items for Blackout v2, depending on what precisely I need. Certainly they can make truly interchangeable parts much more exactly than I can with hand tools.

[keshwyn]

freely-moving pieces are forbidden for stainless steel, but they apparently didn't figure that out until I ordered it.

Why?

[jducoeur]

Don't know -- they didn't say. I suspect it has something to do with the post-finishing process, though: looking at their discussion, it appears that the stainless-steel objects are actually extremely fragile until they're fired in a kiln...

[aishabintjamil.livejournal.com]

Thanks for the follow-up. This is very encouraging. I think I may go try ordering a couple of the more interesting dice people are offering. In a month or so when I'm sure I'm not going to get another unpleasant oil bill for a while....

[fairdice.livejournal.com]

You can get Bathsheba's pieces directly from her web site too — looks like the Triple Torus Pendant is sold out right now, but I'm sure it will be back in stock soon.



I love her metal pieces; they feel great in your hand. (I've never ordered the plastic ones from Shapeways.)

[jducoeur]

Ah -- hadn't occurred to me that she had her own site, but I'm somehow not surprised that you knew about it. Very intriguing...

[keshwyn]

The Noom and the Nexus on her sculpture pages are *gorgeous*. I guess I have something to save up for on my art budget now. Thanks for the link!

[jducoeur]

Note that she also has small versions of them, which are quite a bit more reasonably-priced...

[jducoeur]

OMG -- I think I may have to buy the Klein Bottle Opener...

[fairdice.livejournal.com]

Want to come visit me for lunch again? I'll let you plan with my Klein Bottle Opener — which feels really lovely in the hand — and her Quintron, the mini of which I also have at work.

[jducoeur]

Already ordered one, so I'm going to find out for myself. (But coming over for lunch sometime might be fun, just on general principles, if I can manage to find a decent opportunity around The Crazy here at work...)

[mermaidlady]

Bathsheba and I used to take classes at the same aerials studio and I'd occasionally bum a ride with her. On one of those trips she talked about the technology she used to produce her works, but I forgot all about it until now.