[Ingeniosuccinimide]

One friend from a small pharma company gave me an old Soxhlet extractor. I was planning to have some fun with that, prepare extracts from cinnamon, pepper etc. But he has no thimbles. Which homemade or household thing could be used as a replacement for the thimbles?

I was thinking of folding the coffee filters sveral times, but it still seems to be too weak. Possibly also impure.

[Arkcon]

That does seem a little weak.  Thing is cellulose thimbles wear out over time.  Maybe you can wire together a decent basket out of window screen mesh.  That's if you're sure it can stand up to the solvents and actives you intend to use.

[Furanone]

I have used several wraps of cheese cloth (most made from cotton/cellulose) in the past that you can buy at most grocery stores.

I would run the cheese cloth through as blank (no sample) first to ensure it was free of all impurities, and typically I would find the Soxhlet flask collected no residue (by weight) after evaporating the pet ether out after that blank run. The nice thing about cheese cloth is you can decide how many layers to wrap sample in depending on the consistency of your sample. For really soft oily samples a cellulose thimble for sure would work best. You could tie it at top with a wire as suggested above.