Picture of Beer-view mirror
This is a small rear-view mirror, meant to mount on your bike helmet (or glasses, or baseball hat...) so you can see behind you with just a little turn of the head. It's made from a bottle cap, a bike spoke and nipple, acrylic mirror, and glue.

Materials for one mirror:
Bottle cap (pick a good one!)
Acrylic mirror (TAP plastics has scraps for real cheap)
Bicycle spoke (free from local bike shop, ask when they cut up a wheel)
Spoke nipple (should come with the spoke)
Glue (I like "E 6000" from TAP plastics)

1 1/8" Hole saw (sans arbor)
Access to a Drill press
Dremel tool (not needed, but nice)
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Step 1: Cutting the mirror

Picture of Cutting the mirror
I'm making a bunch, but if you're just making one that's cool.

Take the arbor out of the hole saw. (That's the drill bit in the middle of it, that helps center your hole. Since that would put a hole in the middle of the mirror, we don't want it there.)

Mount the hole saw and mirror on your drill press. Have a punch-out tool (I use a blunt stick) ready. If your mirror piece has the protective film on it, leave it on! It will help keep the mirror surface good throughout the process.

Cut the mirror out, and then swiftly punch it out of the hole saw before the acrylic gets too solidified. If you're doing lots, do one at a time! Filling up the hole saw with stuck-together mirror bits is bad.

Step 2: Drilling out the bottle caps

Picture of Drilling out the bottle caps
In this step we'll drill out the bottle caps to accept the spoke.

Clamp the cap down securely.

Use a sharp nail or the like to punch a small hole to start the hole.

Drill out the hole with a drill bit.

Match the size to your spoke diameter! It's nice if the spoke's threads engage with the hole, it makes it more secure with the nipple. This could be over-engineering, but whatever.
bo88y1 year ago
BTW, if you don't have access to a drill press, try drilling through a 3/4" board with the hole saw before removing the arbor. Then clamp together a sandwich of wood, acrylic, and the piece with the 1" hole on top. Use the 1" hole as the guide for the hole saw. Not as precise, but close enough for beer-cap work.
rustytoy3 years ago
I like it. I might make some for my friends
I have all the parts.... But no helmet.
try mounting it on ur baseball cap.
burnhamish4 years ago
Just finished my first one, used a Bell's Oberon cap (great beer, great cap!). Thanks for the instructable!
goodgnus5 years ago
What is the final diameter of the mirror? I measured a bottle cap and it seems to be barely 1" inside diameter, so I'm wondering if the mirror you're drilling out is just under, maybe 15/16" or 7/8"?
rhm35 years ago
Drilling holes into the inside of your helmet weakens it ability to cushion impact . I suggest not useing this method .
totoroben5 years ago
Nice rendition on the Chuck Harris helmet mirror. I like cap idea because it is already shaped and all you need is a 1" hole saw. The only thing I would add is bending it in a way so it clips on the helmet.
i like this. i had bought some mirrors to make one, but wasn't able to find good cheap wire. i had a busted tire, and didn't even think of using the spokes. the bottlecaps are nice, too. i'm waiting for the glue to dry one one now. i'll be making it so it can be mounted onto glasses rather than a helmet. i also put some rubber tubing over the folded over parts (the parts that you stuck into the helmet) as to not scratch the glasses.
Visitor8 years ago
Have you tried making an S-bend to the spoke and let the glue fasten it to the bottle cap instead of hacking the nipple? Do you leave the plastic seal to the cap on purpose?
Benstar (author)  Visitor8 years ago
I thinkk an s-bend would work fine. I've never tried it, but I can't imagine it being a bad idea. I never used to cut the nipple and assemble it this way, and they worked fine---you just had to be a little more careful tightening from the outside. Peeling the plastic seals out is really hard! So it's not on purpose, it's more laziness. I don't think it makes much difference though---why do you ask?
Benstar (author)  Benstar6 years ago
Ooh, I just thought of why an s-bend is bad: then you have to twist the spoke to change the mirror angle! Not so good. The nipple-nut system means you can position the mirror and then lock it in place.
Aeshir8 years ago
(removed by author or community request)
.......Some people are easily amused LOL
haha spoke nipple lol sorry im very immature sorry
There's a guy in San Diego who makes these too. My wife bought one of these at our bike club. No nipple on this one though, works well. Great idea Benstar.
bumcharge7 years ago
that blue paw wheat ale is good stuff
book worm8 years ago
great idea will have a go i have a miniature pipe bender set i bought for modelling that should do the job.just have to go out to buy some beer now.
mw3 book worm7 years ago
I made something similar with a plastic dental mirror. I heated it up where it bends, twisted it back to a 90 degree angle and attached it to my glasses with a couple of small zip ties.
Visitor8 years ago
I saw these mirrors the first time in a BikePortland report from BikeCraft '06 ( ). Are you the same Ben?
Benstar (author)  Visitor8 years ago
Yep, same guy. I love BikeCraft! Maybe if enough folks make their own mirrors I can see more of the other vendors stuff and spend less time in my booth.
HamO8 years ago
Excellent, very well done, great pics.
hay_jumper8 years ago
Those are some awful fancy beercaps. The only one I can identify is Doghead. What are the other ones? Nice instructable, also. Great photos and text. You get exactly three pats on the back on a one to three pat scale.
Benstar (author)  hay_jumper8 years ago
Thanks! The caps are: ???, Fizzy Izzy (I think), Dogfish, Pyramid (they come in many colors; snowcap has snow on the pyramid), Red Nectar. I made some with the New Belgium caps that were very popular.
ohhh it goes on a helmet.. i thought it was some perverted look up a girls skirt (or guys kilt) mirror thingy.

good instructable. clear and concise =D
That's really nice, I wouldn't bother going to a bike shop thou, a quick look around and it's really easy to find abandoned bikes. Abandoned bikes can be found on the roadside, look around bus shelters and parks, quick work with a pair of bolt cutters and you've sourced all the spokes, and other parts, you'll ever need. that's a joke.