Ranger Bic Sheath.
The name comes for "Ranger bands", which are made from cut up inner tubes and used like bungee cords for packing/clamping things together.
Using the skinniest bicycle inner tube, install a grommet into one end, stick a mini-Bic lighter into other, and attach to your keychain. Get damaged inner tube from your local bike shop. Get grommet kit from Home Depot (in the Tools section).
Source:
http://www.good-kit.com/ranger-bic-sheaths/I went looking for personal fire starter ideas and often read that a Bic lighter is almost foolproof and a mini-Bic will burn for ~30 minutes. That then left the problem of how to attach it to a keychain. After more searching, found above idea and it to me seems to be simpler and superior to all others. Kudos to inventor!
The grommet size shown above is 1/4", but 3/8" more completely spans inner tube width and
may increase water resistance. Bottom line: either size will work okay.
As I don't smoke and seldom need a lighter, I've inserted my Bic with striker mechanism nearest the grommet end. I've also folded inner tube double before installing grommet. Intent was to make grommet end more water resistant and protect Bic striker and gas valve from accidental activation. Bic's exposed bottom lets me check fuel level. (Inner tube can be stretched sideways when installing Bic to prevent it activating gas valve.)
Made one as a gift and recipient wanted inner tube sheath slightly longer than Bic. Why? Sheath then wraps around Bic for better grip. Person only planned to remove/use lighter during an emergency, otherwise would never use it. (I have not had any trouble with my Bic slipping out of shorter sheath.)
Construction suggestion. First, insert grommet into long inner tube section. Second, cut inner tube to fit length of your Bic lighter. Third, insert your Bic lighter into finished sheath. Why? In this order, there is nothing really to measure, so less likely to mess up and finished sheath will exactly fit your Bic.
(Added) Full disclosure. It was this topic that make me start thinking seriously about fire starters and the rule of 3s. The rule of 3s, death comes after: 3 minutes without oxygenated blood, 3 hours from hypothermia, 3 days without water, and 3 weeks without food. So fire/heat is high on the list and I want to keep it's makings light and close.
I bought the magnesium/flint block. It works, but too bulky/heavy for my keychain.
Haven't bought a firesteel, but know I'd also need to add tinder.
During my fire-making search, I kept running across references to Bic lighters as the as the one-stop, light-weight, foolproof keychain solution. Hence my keychain focus here.
My belt pack for hiking carries my other stuff: magnesium/flint block, Fox 40 whistle (large even cut down), signal mirror (re-purposed AOL CD), space blanket, chemical hand warmers, compass, small sheath knife, large SAK multitool clone, food, water, small medical kit, LED headlamp, spare sunglasses, and other stuff I can't remember at the moment. Everything that I've tried and wanted to keep as backup, but decided was too big to carry every day.
Normally when I leave the house I only carry my wallet and keychain. My wallet contains: small signal mirror (cut down AOL CD), and some aluminum foil. My keychain carries: mini-Bic lighter, small HF emergency whistle, small SAK Ranger, P-38, AAA multi-mode LED flashlight, spare AAA battery, large safety pin, ... and my keys. So figure I have covered my day-to-day need for day/night signaling, heat, and water collection.
If I'm going further afield, I add my belt pack, down vest (gloves, REI Buff, knit cap in pockets), and wide-brimmed oil-skin hat. Just buy a few more snacks and refill my water containers and I'm good to go.