Being the cheap and impatient bastard that I am, I picked up some 97¢ wide-neck squeeze bottles at good ol' Walmart this evening. I bought their entire stock (7), with low expectations.

My expectations were met precisely, and 5 of the 7 leaked like an over-dripped RDA. It was clear why; the top of the neck above the threads were very rough or uneven, preventing a tight seal against the lid.

So I had a light bulb moment, and thought, "I can even these out with a razor blade!" Realizing the likelihood of shooting my eye off with a razor blade, I abandoned that idea and thought of an even better way: using a piece of sandpaper laid on a hard, flat surface, like a knife honing stone. This way, by holding the bottle upright carefully, I could maintain a consistent plane across the neck of the bottle, giving it the best chance of sealing against the lid. I did it in two stages, starting with 220 grit, then "polishing" with 1000 grit. Rotating the bottle slightly between strokes helps average things out.

Hopefully this helps some of you other cheap, impatient bastards.