Something you may already know but I'll just mention it because of what you wrote. In the sewing section of the large 'crafty stores', Coates & Clark makes a nylon sewing thread that comes in clear and smoke. It is not fluoro. The label it identifies the the diameter as .004 which makes it 7x. Now I'm not saying that stuff is as strong as a 7x tippet material but I've tried it and it was okay. As a matter of fact, it has very little memory and hardly any looping like typical tippets. Not necessarily recommending this stuff. Just sayin. Oh, it's also good for tying.
also makes a pretty good furled leader....comes in both .004" & .005" diameters