Every July I end up with a shoebox of bottle caps that seemed too pretty to toss and now just sit there judging me. This is the project that finally gave them a job. Instead of gluing caps onto a board or turning them into magnets again, you flatten them, fill them with tinted resin, and hang the whole thing in a sunny window so it throws little blobs of colored light around the room like actual sea glass. It looks way more expensive than it is, and it’s a genuinely satisfying use for all those bottle caps you’ve been hoarding since Memorial Day.
What you’ll need
- 10 to 15 clean, dry bottle caps, mixed metal colors are fine since you’re covering them anyway
- A hammer and a hard surface, or a small vise
- Clear epoxy resin, the kind made for jewelry or small pours
- Mica powder or alcohol ink in ocean-y colors: aqua, seafoam, cobalt
- A tiny drill bit or an awl for the hanging holes
- Jump rings and fishing line or thin jewelry wire
Step one: flatten the caps
Bottle caps have that ridged edge, which is cute on a bottle and annoying in a craft project because resin pools weird around the crimps. Flip each cap upside down on a solid surface and give it a few firm whacks with the hammer until the edges relax and the whole thing sits mostly flat. You don’t need it perfectly smooth, just tamed. This is also a great step to hand off to a kid who needs to get some energy out, under close supervision obviously.
Step two: mix and tint the resin
Work in a well-ventilated spot, on a surface you don’t love, with gloves on. Mix a small batch of two-part epoxy resin following the ratio on the bottle exactly, since eyeballing it is how you end up with a tacky mess three days later. Split the mixed resin into two or three cups and stir in a pinch of mica powder to each, keeping the colors on the lighter, more translucent side so the light can actually pass through. If you’ve never worked with resin before, ArtResin’s safety guide is worth a five minute read before you start, because ventilation and gloves matter more than people expect.
A basic beginner-friendly kit like this small-batch epoxy resin kit is more than enough for a batch of caps, and you won’t be stuck with a giant jug of resin going bad in your closet.
Step three: pour and swirl
Pour a small amount of tinted resin into each flattened cap, filling to just below the rim. Use a toothpick to swirl two colors together in a few of them for that marbled sea glass effect, then leave them completely undisturbed for at least 24 hours. Dust and pet hair are the enemy here, so cover them loosely with a plastic tub or box while they cure. If your mica powder options are limited, a small set like this mica pigment set gives you enough ocean-adjacent shades to mix and match without buying five separate jars.
Step four: drill, string, hang
Once fully cured, tap one and it should feel hard, not tacky, then drill a tiny hole near the edge of each cap or use an awl if the metal is thin enough. Thread jump rings through the holes, then tie them onto fishing line or wire at staggered lengths, the way you’d string sea glass you actually found on a beach. Hang the whole strand in an east or south-facing window where morning or afternoon sun will hit it directly.
The first time the sun actually hits these, you’ll get little puddles of aqua and seafoam light scattered across your windowsill, and it genuinely does look like sea glass rather than bottle caps that used to hold your soda. Swap the color palette for amber and gold in fall, or red and green closer to the holidays, and you’ve basically got a suncatcher for every season using the same pile of caps you were about to throw out anyway.
