If you don't have a test tube rack in which to hold your test tubes of perfume formulation experiments, use a short container, an empty 1 lb cocoa butter container from Mountain Rose Herbs works great, fill it with fine crafter's sand and poke the test tube into the sand to hold it upright. You can fit three or four test tubes into a 1 lb cocoa butter container.
If you don't have a fancy schmancy scent strip holder, try gluing those little crafter's clothespins (the crocodile ones with springs) onto popsicle sticks and stick them in the sand too. Then just clip on the scent strip.
Fact: lab filter paper is optimal for filtering finished perfume and eau compositions (you can get them on ebay and they're used for filtering wine), but don't expect the composition to flow through like it does when you use thinner coffee filter paper -- what takes moments through a coffee filter paper will take an hour or more through a lab filter paper.