Culled from paint deposits in old car factories, these may look like exotic gemstones, but their colors reflect years of layering and hundreds to thousands of assembly-line stops. They are frequently referred to as Detroit Agate, or simply: Fordite.

Workers at the time, and urban explorers in later years, grew fascinated and started chipping off the results to save and ultimately shape into jewelry and other objects.

Historically, automotive bodies were painted by hand, and the spray-painted layer would drip onto surrounding surfaces and equipment (or simply be coated indirectly).

The pain would end up backed onto these surfaces, where it would solidify and grow thicker over time, up to inches over the years.

Like layers in a rock to a geologist, these faux-minerals tell stories of automotive history through their vibrant and varied colors, including changes in favorites over time. While you can still find this in raw form or polished pieces online, be warned: pre-1970s layers may contain lead.

In what appears to be the first recorded work of public aerial drone vandalism, this off-the-shelf quadcopter was hacked to hold and use a can of spray paint, forever transforming the landscape of potential graffiti targets (image above by Arthur Holland Michel).

Attacking a giant Calvin Klein ad in the heart of New York City, this modified Phantom drone sprayed red paint on the face of model Kendall Jenner, able to fly up to and hover around the area of application much faster (then escape much easier) than a human ever could, finished in under a minute. Robot-made murals and computer-generated street art are nothing new, but putting them in the sky could change everything.

The artist behind this intervention, KATSU, has been exprimenting with drone-mounted spray cans for some time now in controlled indoor environments, but wanted to show the potential for his work to reach places inaccessible to humans.

More proof of concept than finished piece, this particular work of graffiti was difficult to accomplish, with a great deal of effort put into stabilizing the aerial robot – creating a tag with any kind of precision using this method would be effectively impossible.

Per Wired, though, the implications are bigger than this test: “Given the enduring privacy, safety, and legal concerns around the technology, conceptually it makes a certain amount of sense that it would find uses at the peripheries of what most people (let alone the law) would consider acceptable. KATSU’s scribble high above SoHo might not look like much, but it represents the potential that drones have to transform graffiti forever.”

The nature of graffiti tends to result in nocturnal excursions, but painting completely in the dark can be a be problem and sometimes you just need a little bit of light.

LASH is a light attachment for spray cans designed by Subinay Malhotra of New Delhi, India to provide low-level illumination on demand to artists on the street.

The device slots onto the can and charges via a motion familiar to anyone who has sprayed paint, illicitly or otherwise: the shaking action one has to repeat to keep on painting.

The LEDs are intentionally dim and easy to turn both on and off at the push of a button, all so artists can see what they are doing on an as-needed basis but blend back into the shadows with a simple click.

NeverWet has been making headlines as the silicon-based spray that repels liquids from clothes and electronics, but this off-book use shows another fascinating application that may be even longer-lasting: urban art invisible until poured upon.

As part of a Home Depot competition, Nathan Sharratt decided to create stencils and spray hydrophobic NeverWet onto streets and sidewalks, resulting in areas of deflected moisture surrounded by soaked concrete. Like invisible ink, the water-repellent areas remain hidden until another liquid is applied (instructions at the end below).

Given criticism of NeverWet when applied to shoes (apparently it can discolor or leave residue) and phones (touchscreen and durability issues have been reported), this may prove to be a more persistent, if unintended, long-term application of the product.

And for any interested subversive artists, it could prove a unusual boon when bothered by police: how will the authorities justify arresting someone for spraying an invisible coating on a public surface? Meanwhile, best of luck to Nathan in the contest – a win here is surely deserved! As one reader  noted: there are practical and legal street applications of this too, potentially: “Instead of a sign saying slippery when wet… graffiti saying slippery.” That, and consider: sidewalk happy-hour signs for drink specials in the rain, or way-finding messages for seeking shelter in a storm. Many interesting possibilities.

Short-form instructions for those looking to (officially: don’t!) try this at home or in the neighborhood: “Step 1: You need a stencil. You can do something simple or use an image that includes a fair amount of detail. I created my own stencils from cardboard, but there’s no reason you can’t use a ready-made or store-bought stencil. Just know that NeverWet will get sprayed on that, too. Step 2: Place stencil on concrete. I recommend that you only try this on light-colored concrete for best results. Step 3: Spray the NeverWet into the cut-out areas of your stencil according to the manufacturer’s instructions found on the label. I did two base coats and two top coats.”

Artist Mirko Reisser has long developed a highly personalized (and profoundly cool) approach to making two-dimensional tags appear three-dimensional on surfaces, but in this unusual project, he created an actual physical object out of sand.

Like anyone building a fort or castle on the beach, DAIM was well aware of the time limits and necessarily temporary nature of this little installation – he documents the role of the tide in first encircling, then destroying this sculptural graffiti.

And in case you have not seen is other work, here are some more traditional spray-painted pieces. He has plenty of street tags too, but it’s clear that with the time, space and security of an indoor venue, his attention to detail is able to add incredible depth and dimension to his work.