It took 5 days and I had to restart it after a failure. This was the first failure I dealt with over 9 deployments. It’s remarkable given how many things can go wrong. I optimized pen travel so much that I ended up with a ginormous penstroke that took too much memory for the Pi Zero. Now my later software stacks can deal with that, but this here is old reliable, and I’m afraid to give it an update. I’m still refining the process and learning how to avoid folds in this much paper. It’s tricky.

The base picture is compelling on its own, the algorithmic artifacts rendered over several days give it a whole other dimension.

I didn’t put a sign in front of it. I don’t want to give credit to Russian culture at this point, even from a century ago. I was ok plotting it in public only because the past is a foreign country. But the present can go suck on a rock.

I prototyped several versions at home, really there is much there that is left unposted. Oh well.

I don’t care what civilization you are, you gotta have a Sun deity.

The glint is good, but it comes with a traveling vertical line that reflects the light source. I need to see if I can treat the surface to avoid that before etching. By happenstance I found that a rectilinear light source (office neon) perpendicular to the etching works better than a single light source pointed at it. It covers more vertical angles of viewing while not diffusing the horizontal effect. Running it parallel, much like a diffuse light source, ruins everything. I should draw how this stuff works a bit.

I lined it up with a big public event and tons of people got to see it.

No sure if there’s anything more to say about lasers & post-it portraits, it was the now usual formula. I’ve enhanced the pipeline some to do auto-face-cropping as it is a step we usually waste lots of time on. Esther & I rehearsed over the week end. She runs the operation during the event.

Some recurring questions I get asked at these events:

“What are the machines for normally?” Nothing, their sole purpose is to drag pens and shine cat lasers.

“Is this your job?” Nope, just a side quest.

“So how does this work?” I try to see what part they’re interested in before I launch into a 3 hour tirade :).

“Did you build this?” yes.

It’s very gratifying to see people stare at your work for a while. You can see the gears turning in their heads. I’ll sit by the big machine sometimes to watch people’s reaction to it. When I swap its pen people will come up and tell me how much they like it. I’m just glad for having the opportunity to do something cool in the world.

I was maybe a little too motivated and brought several machines, almost my whole apparatus, and deployed them in various modes. 1 PewtyBot, 1 Mirror PewtyBot, 1 PlottyBot & 1 SkecthyBot doing portraits, and 1 PewtyBot people could control with their phones. The laser portraits worked wonders again, but the original PlottyBot drawing post-it portraits worked even better.

People were clearly keen on getting a tangible souvenir from the evening. Having a robot draw their portraits on a Post-it note struck a chord hard. I think what I’ve learned from this event is that while the lasers throw a lot of pazzazz at you, they are more complex machines that most people don’t try to engage with beyond taking in the light show. While a pen based machine is doing the same thing you’d do with your hand so it’s more approachable to be curious about. As usual a small fraction of them were fixated beyond reason on watching the machine at work. There has to be a “drawing automaton obsession” gene present in ~10% of the population.

Unfortunately, I only had one PlottyBot doing the Post-it portraits, and they take much longer than the lasers so I spent much of the evening trying to keep track of a queue of people who wanted one.

I built 2 4’x4′ photoluminescent paper holders so I could deploy this easier. In the past, finding a decent spot on a wall for the rolls and unrolling them was difficult and time consuming. I also have plans for doing random outside events at dusk in random places this Summer, which is why having something deployable was worth the construction effort. I tried it some already at home last Summer and it’s kind of cool to have the lasers go on a warm Summer night.

I had several people ask me if this was AI :), this seems to have become the go-to explanation for anything tech based that can’t be explained easily. Much like Clarke’s law that “Any sufficiently advanced technology is indistinguishable from magic”, only now it’s AI instead of magic. I’d respond that it was just good old organic grain-raised free-range “I”.

As usual, it was very hard to capture the coolness while manning it so I don’t have much visuals to represent what went on. Ultimately it’s just me running 5 machines, a software stack and talking a lot. Suffice it to say people were into it and I’m emboldened to keep trying public events. Fun times!

Without light

with light

It feels different in person. What’s funny with this specular stuff, is how enthralled I was with it when I didn’t understand how it works. But now I kind of don’t see what the big deal is. I have to remind myself it’s really cool to keep forging ahead.

Since I can control pressure, I’m trying all sort of materials and pressures. I’m literally throwing under the tip any garbage that looks like it could yield a glint, and getting good surprises. I’m of course trying the classics like acrylic and aluminum with various pressures, again to find the best parameters.

I have the tip go very carefully down until it reaches a pressure of 20g, and then it tries to maintain it while moving. Between the incessant taring, and the slow motions, it’s made everything a thousand times slower. I don’t care though, I can do other things while it works.

The machine makes really cool noises with all the extra stuff to find the right pressure. Simply keeping an ear out while doing other things has been a great tool to debug and improve algorithms.

And well, the results are mitigated so far, but I’m getting somewhere with a moving glint effect.

I need to tune the machine to barely touch the medium, and figure out model creation. Moving a tip is easy these days, unsurprisingly though there are a lot more intricacies to uncover to get good results.

Turns out most ballpoint pens’ tip & ink reservoir fit perfectly inside a turkey feather. So the kids will be able to rock their turkey pen at school.

I found the image in a 1902 edition of the Sears catalog where they sold it for $14.95. I consider it an expression of culture, from a time when anything we created came with ornaments. It shines all the more in a modern building with very clean and sanitized architecture.

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The new recursive inset fill algorithm is incredible and making me want to revisit previously hatched plots.

I found a bunch of really cool engravings in some very old books I found in the abandoned house. These books are worthy of some discussion on their own much like the old vinyls, but this isn’t the time.

I got ChatGPT to make me a few SVG handling tools that are really incredibly well done and will help me shed some of the apps I was using. With SVGs there really is not a single app that does all the things, so I drag a collection around just to use 1 or 2 of their function. AI is helping me write scripts to explore algorithms and replace more trivial functionality from apps.

Case in point: this super cool recursive inset fill algorithm to turn fills into something a plotter can do.

I’ve been wanting to write this one for a while, but I knew it’d take me a good few days to nail it. That got turned into 30 minutes with AI. Jaw dropping. I love the effect as it echoes a lot of bored fillings of shapes I’d do as a kid getting bored in class. The cookstove above is filled with it, but it’s far too dense at this size and so it really looks like a actual fill rather than a particular effect.

A lot of my tooling these days is Python which has good libraries for handling SVGs. I used to dislike Python for their dumb purist move from 2.7 to 3 which wasted everyone’s time, and because they had managed to reimplement library hell. But I have to say venv is a successful redress to the later.

It really isn’t the most accurate machine, the belts inside aren’t timed, but it does pretty ok with some rendering algorithm and is fun.