I should probably start by saying I’m not an expert in Buddhist practices or those of just about any other religion. The sum total of my knowledge in this area was picked up from Chinese restaurants, re-runs of Kung Fu and the occasional PBS documentary. Somehow amidst the Honey Walnut Prawns and pledge drives I’ve become aware of an exercise practiced by Buddhist monks that I find fascinating.

Tibetan Sand Painting is an ancient art where monks creating beautiful and exquisitely detailed pieces of artwork with colored sand. It’s a labor-intensive process that can take days to complete, and the results are amazing. But when the art is completed they simply brush the sand away destroying the image. It’s a metaphor for the fleeting nature of life. That’s always seemed intriguing to me – creating something just to destroy it. Now I’m not sure if this next part is true or not, but I recall hearing that they destroy the artwork the instant it is completed. There’s no sitting around gazing upon their work in awe and high-fiving each other. The point of the creation is the destruction and nothing else. So the logical thing to do upon its completion is to immediately trash it. It’s religious meditation as punk rock. Maybe that’s why this idea is appealing to me.

This practice is appealing to me in theory, that is. There are a lot of things I like conceptually but really it’s the idea I like and not the doing. Flying in an F-16, for example, is an incredibly attractive thing that I hope I’m never rich enough to actually do because apparently every non-pilot who has done it has hated the experience. I can appreciate things that others do without actually doing them myself. I don’t actually need to be destitute and living on a diet of White Russians and bowling alley nachos, because The Dude is out there takin’ ‘er easy for all of us. Similarly, I don’t need to destroy my handiwork because The Monks are out there reminding us all of how fragile our existence is while I watch them on my flat-screen TV from the comfort of my couch.

45 Watts of Enlightenment

These thoughts were far from my mind as I started my cutting job on the Epilog Laser at Techshop. It was my first test of my laser-cut paper halftoning technique and I was cutting out a photograph from some cardstock. I created a linear halftone that consisted of a bunch of parallel lines where the thickness of the line varied according to the darkness of the image. Here is a close-up of the vector image I was cutting – if you squint or back up across the room you can see that it’s a pretty good effect.

It’s quite an intricate design that needs to be cut, but fortunately the laser cutter is doing all the work. Several minutes later the Epilog beeped indicating the job was finished and I pulled out the finished work.

Have you figured out where the story is going yet?

I picked up the piece of cut cardstock and for a brief fraction of a second the image of the photograph hung in mid-air before collapsing into a pile of confetti. I immediately recognized my error – each diagonal line was completely separate and thus had nothing to hold them together. I had turned the Epilog into a $30,000 paper shredder. As the pieces of paper fluttered to the floor I was reminded of the impermanence of existence and felt an overwhelming craving for Mongolian Beef. But lunch and enlightenment would have to wait, because I needed to finish my project.

I decided to try a fairly simple fix. In CorelDraw I created a rectangle that was as tall as my image and .02 inches wide. I then duplicated it several times so I had a series of vertical bars and then used the Weld command to join these bars to my image. Finally I trimmed the edges so there weren’t any bars poking out past the edge of the photo. The result looked something like this:

The results came out far better than I expected. The vertical lines were thin enough to not distract overly from the image, but were substantial enough to hold the paper together very well.

Lesson Re-Learned

It’s not like you need an advanced degree in topology to avoid a mistake like this. Most of us learned these principles in Kindergarten while cutting shapes from construction paper. It’s obvious in hindsight that the laws of physics apply to a laser cutter just as much as they apply to blunt scissors. But making the mistake is the best way I know to assure you never make it again.

One of my favorite toys at Techshop is the Epilog laser cutter. It can cut and etch at resolutions up to 1200dpi. It can cut through things like paper, cardboard, acrylic and thin wood as well as etching into those materials, metal and even food.

Lately I’ve been experimenting with creating pictures by cutting pieces out of colored card stock and stacking them up. The way to think about it is that each layer of paper gives you a single color – it’s like a 1-bit monochrome bitmap that’s either the color of the paper or transparent showing what’s behind it. Newspaper printers figured out ages ago how to deal with a similar set of constraints – a single ink color, but high resolution of ink placement – and approximate multiple shades of color using a technique called half-toning. Here’s how I adapted this technique for paper-cut images.

My first test was to see how I could approximate a gradient fill. I started by creating a jpeg image containing a simple black-to-white radial fill (left). Then in my paint program I converted the grayscale image to a monochrome black-and-white image. When you do this in CorelPaint it gives a variety of options on how to do the conversion. One of them is creating a half-tone image, which is what I used. I created a halftone using squares (dots are the ones you see in newspapers) at a 45 degree angle and a very low resolution of 7 lines per inch. The result is the picture on the right.

Now I needed to turn this image into vector outlines so the laser cutter can deal with it. I imported the bitmap into CorelDraw and used the bitmap tracing feature to trace it in line-art mode. Corel’s tracing is fairly flexible and can attempt to trace multi-colored images by creating vector shapes in different colors. Sometimes even if you feed it a simple picture, things like anti-aliasing artifacts can trick it into using a bunch of colors which I didn’t want. Using line art tracing settings gave me a shape containing about 1500 little vector polygons that approximated the half-tone bitmap. I gave the shape an empty fill and hairline outline which tells the laser cutter to perform a cut of the outline rather than a raster-scan etch. The result looks like the image below.

It turns out the hardest part of the project was getting time on the laser cutter. My schedule has been very busy and between travel and working evenings and weekends I’ve only had a few chances to get to Techshop recently. The two laser cutters are very popular so it was almost 2 weeks before I had a chance to try it out. I cut at 600dpi, 100% speed and medium-low power which gave good speed and minimal charring. They call it a cutter, but what it’s doing is burning the paper, so too high a power or too slow a speed will end up with visible burn marks on the paper. A fire in the machine is a possibility as well and before they let you use the cutter you have to take a safety class where they force you to deal with a fire, which is not nearly as exciting as it sounds but still awesome.

I cut it out of dark brown card stock and then placed it on top of a background of red construction paper . The result is a radial ramp from red to brown that looks pretty good. I could have made the squares a lot smaller, but wanted them to be fairly big and obvious. Also, the file took 10 minutes to cut as it is. With a lot more polygons it would have increased the cutting time significantly.

You’ll notice that in the middle the halftone squares got so close they ended up touching and it cut the entire middle out. I didn’t worry about it because this was going to be the background for a picture and the middle would end up being covered. The full finished picture was a picture of a tea drink my daughter likes which you can see below. The additional layers are glued on top of plastic and acrylic spacers to give the whole image depth and the upper layers actually cast shadows on the lower ones.