A while ago I bought a double handful of Grizzly's H7615 oil cans,
http://www.grizzly.com/products/High-Pressure-Oil-Can-5-Oz-With-Steel-Nozzle/H7615
intending to color code them for contents (black cutting oil, way oil, etc.) and keep a set at each of my machine tools. Turns out the seal between the lid and the body is kinda lousy - very thin, and it either kinks or gets displaced when you try to screw the lid on.
Decided I needed to make some substitutes ... but where to find something of the right size? Well, I came upon some sealing rings in the plumbing section of a local store that had the right ID, but much thicker than practical and some had too large an OD. I recalled a trick I'd used many years ago - mounting an Exacto blade in a holder large enough to grab in the lathe's QCTP. First photo shows my current effort. Note that blades can be mounted at either end, so by mounting the holder on either side of the QCTP base, and cut either a diameter or a length.
Second photo shows the blade splitting a 0.144" wide ring (mounted on a PVC pipe arbor) into three rings 0.048" wide. Obviously, with such a thin, flexible blade (Exacto #11), you have to be perpendicular and advance slowly and carefully. But it cuts beautifully! Rough measurement of the rings with a caliper verified their thickness came in within about 0.005". If you need something stiffer, you can extend the backing further along the blade, or else go to a #24 blade.
Third photo shows both a large OD ring cut down and the perviously large OD and small OD rings cut to thickness, as well as one of the rings in place in an oil can lid. WORKS!!!
PS - What's going on with the file (photo) upload process?????? They don't show up in the "composition" box, but do seem to make it to the post. Disconcerting, to say the least!
Another PS - Looks like Griz is closing these oil cans out - just $0.99 each right now!