If you’re looking forward to the total solar eclipse this week but weren’t able to buy special eclipse glasses, you could still be in luck with a homemade viewer that allows you to safely watch the once-in-a-generation event.
Those who want to watch Monday’s solar eclipse will need special glasses that will shield their eyes from the potentially damaging sun rays, and many stores have already sold out of these specialty glasses. But NASA is stepping in to help those who didn’t buy them in time, offering some instructions on how to buy a perfectly safe solar eclipse viewer with items you likely already have in your home.
In an interview with TIME for Kids, NASA Solar Eclipse Educator Charles Fulco noted that this viewer allows people to see the eclipse without looking directly at it.
“What I like about a solar viewer is you don’t even look in the direction of the sun so there’s no chance of anyone hurting their eyes,” he said.
That could be a big risk. As experts note, the solar eclipse will magnify the power of the sun’s rays and can be incredible dangerous to view without some kind of protective glasses.
“Imagine almost like a magnifying glass. The 10-year-old boy that looks at an ant using a magnifying glass. The same effect can happen in your eye,” Dr. Sam Teske, owner of Eye Doctors of New Tampa, told Fox 13 in Tampa.
“The issue is called solar retinopathy, where you can actually burn a hole in your retina, and damage the back part of your eye.”
To build an eclipse viewer, all you need is a shipping tube, tinfoil, a hobby knife, tape, a marker, and an awl (which is used for punching holes).
Here are the steps on how to make your own eclipse viewer (via TIME).
Step 1. Using the hobby knife, cut a small hole in one end of the tube. As Fulco explained, the smaller the hole is, the more clear the eclipse will appear.
Step 2. Tape a piece of foil over the hole, then punch an even smaller hole in it using the awl (TIME suggests using safety goggles for this step, if you have them).
Step 3. On the opposite end of the tube, cut a large rectangle to serve as a viewing window.
For those who learn better by watching, the video below contains all the steps needed to make your own homemade eclipse viewer.
That’s all there is to it. During the solar eclipse, you can take your homemade viewers and hold it over your shoulder, with the small hole facing the sun. You will then be able to view the solar eclipse through the rectangular hole you cut out.
[Featured Image by Scott Olson/Getty Images]