Look for small medicine bottles in antique stores. You want one that doesn't show casting seems. It should be greenish in color( Brown came later), and have a few bubbles in the glass, from being blown into a mold. Put a cork stopper in it.
To secure it, you can sew(stitch) leather around it, wet, which will shrink against the bottle when the leather dries. Put the smooth side of the hide against the glass, and the rough side out. That is the easiest way to distinguish by feel the difference between a bottom of spirits, and your cleaning fluid! This protects the glass bottle from nicks and small cracks from banging into other items. The leather will also cover any Label that was molded into the glass body.
I have a 2 oz. medicine bottle of this type, which cost me about $.50 at a flea market. I have not wrapped mine in leather, yet,because the blown glass is so thick it seems almost indestructible. Its rattled around now in my hunting pouch for more than 25 years, so I can't get in a hurry to do that stitching work.
