How to make coasters that connect guests to your Wi-Fi with a single tap

In this world, only three things are certain: death, taxes, and the fact that houseguests will eventually ask for your Wi-Fi password. What’s also certain is that, regardless of how simple your password is, you’ll inevitably be bombarded with questions after you recite it. “All lowercase? Any spaces? How do you spell colonel? Why are you so obsessed with KFC?”

Well if you’re sick of going through the same song and dance, and want a more slick and secure way to let your houseguests access your network, we’ve got a simple DIY solution for you: NFC drink coasters that grant guests access with just a tap.

NFC is one of the coolest technologies ever. Short for Near-Field Communication, it’s essentially a method of wireless data transfer that detects devices in close proximity, and then enables them to communicate without the need for an internet or Bluetooth connection. On top of that, NFC tags don’t need batteries to work. They can store small amounts of information passively, so you won’t ever need to recharge your coasters.

Better yet, despite how awesome and techy these coasters are, they’re also incredibly simple to build. You can easily make a whole set of them in under an hour, with minimal materials and expertise. Before you get started though, it’s worth noting that you’ll need an NFC-capable smartphone running Android 5.0 or later in order to execute the steps below. There are ways to achieve the same result with an iPhone, but they are vastly more complex. Sorry iPhone users!

It’s also worth noting that if you already have coasters you like, you can skip the whole “make your own out of concrete” part of this tutorial and upgrade the ones you’ve got. Just snag some NFC stickers, put ’em on the bottom of your coasters, and follow steps 6 and 7 of this guide.

Here’s how it’s done!

Tools & Materials
DIY NFC Coasters

Instructions

Step One
DIY NFC Coasters

Mix the concrete according to the instructions on the bag. The amount of water you’ll need will vary depending on the type of concrete you’re using and the amount you’re looking to make. Generally speaking, you probably won’t need more than a pint of concrete to make a full set of these coasters, which means you’ll only need a couple ounces of water. It’s not an exact science though, so feel free to adjust your mix until it has a nice, thick consistency. Make it too soupy, and not only will the concrete take longer to dry, but it’ll also produce weaker coasters that are more likely to break.

Pro tip: If your concrete mix has lots of big rocks in it, pour it through a metal sieve to sift out the chunky stuff. This will result in a smoother, more consistent concrete mix. 

Step Two
DIY NFC Coasters

Pour a small dollop of your wet concrete into the bottom of each one of your petri dishes. You want just enough to create a super thin layer. Tap the dishes on your work surface to level out the mix and make it settle. Again, this isn’t an exact science and it doesn’t have to be perfect.

Step Three
DIY NFC Coasters

Grab your NFC stickers and place them in the center of the concrete-filled petri dishes. It doesn’t matter if they’re upside-down or right-side-up — they’ll work just the same regardless of orientation.

Step Four
DIY NFC Coasters

Pour some more concrete into the petri dishes. You want enough to completely cover up the NFC sticker, but not so much that your coasters end up being too thick. Just drop in a small dollop and tap the dish a few times to make everything settle. Don’t worry about making the top perfectly level — this is actually going to be the bottom of your coaster, so it’s okay if it’s lumpy and mildly uneven. After that, let the concrete dry for at least 24 hours, or whatever the instructions on the bag recommend.

Step Five
DIY NFC Coasters

Remove the dried coasters from the petri dishes. This will likely require a bit of tapping, pushing, and prying — but don’t be too rough on them, or you risk fracturing the coasters before you’ve even had a chance to use them. They should come free fairly easily, at which point you’re free to place cork pads on the bottom. Use three pads for each coaster to avoid wobbling, and try to place them midway between the outside rim and the center to avoid breakage under load.

Step Six
DIY NFC Coasters

To program the NFC stickers, take the following steps. First, enter the Settings menu and turn on NFC. Second, make sure you’re connected to the Wi-Fi network you’re hoping to program into the tags. Third, enter your phone’s Wi-Fi menu and do a long press on the network you’re already connected to. A contextual menu should appear with the option to “write to NFC tag.” Tap that option, and then place your phone on the coaster. This will transfer the network login information to the NFC tag.

Note: You might need to experiment a bit to find the exact location of your phone’s NFC reader. Most are positioned near the center or top, but it differs from phone to phone. Just scoot your device around until you find the sweet spot.

Also, if you don’t see the “write to NFC tag” option appear, and you’re sure you have NFC turned on, then check your network permissions. In some cases, more restrictive networks won’t allow you to copy their information and write it to an external storage device.

Step Seven
diy nfc coasters weekend workshop coaster wifi complete

Repeat the “write to NFC tag” process for the remaining coasters, and you’re done! To test that everything works, just disconnect from your Wi-Fi network and tap your phone on a coaster. If everything went smoothly, you should be given a pop-up menu that asks if you’d like to connect.

After that, all that’s left is to leave these suckers all over your house! Just remember that you and your houseguests will need to have NFC turned on before tapping on the coasters — otherwise your phone won’t read the tags.

Product Review

Traeger’s Timberline smoker starts to get smart, but isn't ready to graduate

Renowned for its line of wood pellet grills, Traeger has taken its game to the next level with the Timberline 850 Wi-Fi-controlled grill. Just how smart is this smoker? Read our review.
Emerging Tech

Regular Wi-Fi can accurately detect bombs, chemicals, and weapons in bags

Surveillance cameras and bag searches have become commonplace when it comes to security in public venues. But researchers may have found a different way to detect suspicious items: regular Wi-Fi.
Photography

The Nixplay Iris might just make digital picture frames cool again

The digital picture frame's popularity has fizzled because of time-consuming updates and low quality -- but can a Wi-Fi connected frame change that? The Nixplay Iris is an 8-inch smart digital picture frame that wireless updates photos.
Mobile

Need to record calls on an iPhone? Check out our handy guide

Are you wondering how to record calls on your iPhone? It isn't as easy as you might think, but we'll walk you through the process of doing so with Google Voice, and identify several other apps and external voice recorders that can help.
Mobile

Here's how to use iTunes to make a customized ringtone for any iPhone

No one likes to pay for ringtones -- or anything else, for that matter. So hang on to your precious money and check out our comprehensive guide on how to make ringtones for an iPhone using iTunes.
Gaming

How to connect a Nintendo Switch controller to your PC

Nintendo's Switch controllers, including the Joy-Cons and the aptly titled Pro Controller, use Bluetooth, which makes them compatible with your PC. Here's how to start using them for PC gaming.
Smart Home

How to set up your Lenovo Smart Display

Here's how to set up your Lenovo Smart Display, including what information you need to provide to the Home app and how to choose the right Google Assistant settings for your new smart screen.
Social Media

Your Twitter name can change with the times, just like you do -- here's how

Despite what you may or may not have heard, Twitter names aren't actually set in stone. Check out our quick-hit guide on how to change your Twitter username and display name in less than five minutes.
Home Theater

How to buy speakers: A beginner’s guide to home audio

From the difference between bookshelf speakers and monitors to the proper way to audition, our ultimate speaker buying guide has all the information you need to create your own home audio nirvana.
Cars

How to watch Formula 1 online

There are plenty of Formula 1 races every year, many of which take place in some of the most beautiful cities in the world. Check out our brief guide on how to watch Formula 1 online, if you're looking to keep up on the action.
Mobile

Is your smartphone frozen? Here's how to reset your iPhone

You can do a lot with an iPhone, but if you ever run into an issue with it, the first thing you should do is restart it. In this guide, we tell you how to reset your iPhone, and explain how it differs from a factory reset.
Movies & TV

How to watch NFL games online, with or without cable

The NFL's 2018 season is here, and we know you don't want to miss a moment of the action. Our comprehensive streaming guide will show you all the best options to watch the games online so you can make the right choice for you.
Mobile

How to find a lost phone, whether it's Android, iPhone, or any other kind

Need to know how to find a lost phone? Here, we’ll help you locate your lost or stolen phone using both native and third-party apps and services, whether it’s a smartphone or an older variety.
Home Theater

Become a master caster with these Google Chromecast tips and tricks

Google's Chromecast and Chromecast Ultra are the ultimate budget-friendly streaming devices for cord cutters. We've put together a list of our favorite tips and tricks to help you get the most out of your Chromecast.