Monthly Archives: November 2013

A Little Relief



Last week I came downstairs to find the elder Zhengspawn had gotten into my box of acrylics and was busily painting one of the myriad bloxen that lurk in the crevices of Casa de Zheng. The original was printed in clear PLA on my Printrbot Simple; I think this is a nice improvement.


I thought it’d be fun to give her paint job a little relief and re-release it as a new bloxen.

The first step in the process is getting the real-world paint onto the 3d model. The easiest way I can think of to do this is to photograph the painted block and then texture map the model.

It occurs to me that I could also have used Autodesk’s 123dCatch to capture the surface of the bloxen, but Lao Zheng is old school, or what passes for old school in the 3d modeling world, and dislikes giving tessellation tasks over to the Cloud.

So photographs it is, just five of them since I’m not doing anything to the bottom of the model; one snapshot for each of the four sides, and one photograph for the top.

Next, I’ll take a basic bloxen and set up a UV map.

UV coordinates on a polygonal model are roughly analogous to latitude and longitude on a globe; they tell the paint where to go on the model’s surface. The first step in assigning UV’s is to unwrap the model’s surface and lay it out on a grid. There are automated processes for this in many applications, but with a model this simple it’s probably easiest and most intuitive to do it by hand.

block uv

And here’s the bloxen with a loose texture map on it. I’m not going to worry about the underside of the model for this project because ultimately it’s destined for 3d printing and the bottom needs to be smooth so it’ll stick to the print bed. Some of my textures are out of focus and distorted and I didn’t bother to texture the sides of the tenons, but I’m just using the painting as a rough guide anyway.

bloxen textured

You can download the UV’d model if you’d like to mess around with it yourself. Converting to STL wipes out UVs so the model’s in OBJ format. Enjoy.

The next step is to subdivide the mesh many, many times so that Maya’s paintbrush tools have some vertices to work with.


Most of the setup is done and now there’s a fun few minutes of using Maya’s Sculpt Geometry tool to bump out the vines. (Flowers will come later)

unforeseen problem After a bit of painting I find some WTFfery going on amidships, so this requires a step away from creativity and into the realm of Just Fixing Things. It looks like there is a line of extra small polygons in there, probably created by the subdividing script I’m using. They’ve gotta go, and sometimes the best way to fix things is to Just Delete Them.


The process destroys my nice quad-only mesh but I’ve been to enough rodeos to know that this probably isn’t going to sink the model later. Moving on, I make a bunch of little flowers, rotate them randomly, and stick them onto the surface of the bloxen.

add flowers

The flowers are very simple models so booleaning them to the bloxen is easy, except for the one flower that rounds a top corner. This one needs to be bent a little bit before it can be added.

deform flower

After adding the mortises on the bottom of the bloxen, merging all the stray vertices, and checking the model in netFabb to make sure it’s manifold it goes to print. No problems whatsoever, which is strangely disappointing since my 3dprinting failures Pinterest board hasn’t been updated in a while.

Ever since I replaced my delrin plungers with an extruder upgrade and switched to a BB ball-bearing based filament spool my MakerBot’s been rock solid.

This little project got me thinking in new directions, so #staytuned for an update sometime in the next few weeks.

Toil and Trouble, Part I

So. Another Halloween has passed, and while the denizens of Casa de Zheng did manage to get some nice homemade costumes out the door, it’s been another year of postponing bigger Halloween projects because I’m Just Too Busy Right Now. For years I’ve wanted to make a classic black cauldron over which The Lovely and Talented Mrs. Zheng3 can stand on All Hallows’ Eve, dispensing hot cider to chilled trick-or-treaters with a cackle and a grin.

She does have an adorable cackle.

A fortnight past I was discussing Halloween projects with a friend and neighbor and I lamented my lack of time for such things. I’ve wanted to engineer monstrous spiderwebs and motion-sensing jump-scare zombie automatons for years but always get too caught up in Halloween costumes and daily minutae in the weeks before the big day to ever get to even starting any of these grand designs.

The hard truth is that there is never enough time for such opuses. Some meeting, some job, some illness, some obligation always interferes, and it’s just too easy to sleep in until 7am on a Satudray. And yet this cauldron must be made.

If not me, then who? If not now, then when? Am I to wait until the youngest spawn has wriggled off to college, when I’ll finally, finally! have the time to pursue every creative project of which I can conceive, unhindered by the demands of short mutants who share slightly less than half of my DNA, when the dawn of retirement peeks over the horizon and the iPhone 9 announcement is nigh?

No. If it is to be, it is up to me to do this now. As important as getting the project done is instilling by example the creative process into my kids. To plan, to build, to fail, to learn, to feel finally feel the pride in a piece of art just-completed and yet never quite done.

The deadline: Full beta testing in September 2014. Public release date October 31, 2014.

The requirements, purposefully done in broad strokes:


  • The cauldron’s got to be big enough to be impressive, even when it’s just sitting there doing nothing.
  • It must be light enough to be easily moveable, but strong enough to withstand some jostling in case a child bumps into it.
  • Must support a hot plate for cider mulling.
  • Must be non-flammable.
  • Non-toxic eerie smoke needs to pour from the top of the cauldron while it’s in use. Dry ice, maybe?
  • Drizzle-proof would be a nice touch.

The inside of the cauldron must glow.
Needs variable-intensity fake fire underneath.
Must run unattended in an idle mode, and also needs user input for choreographed performance.

Determining scale is the first order of business. We own a circular patio table that would make an excellent jig for bending the cauldron’s armature, so I’ll use that for reference when figuring out just how large this cauldron should be.


Winter is coming (natch) so much of the construction will likely wait until spring, because I think this will be too big to fit through the doors on the house and it’ll have to live in the garage.

Goal for next week: get the mouth of the cauldron bent into shape. I can make a hoop in a week, right?