unconventional mouse toys

[Chocobo Prime]

I'm really broke and can't afford a lot of toys for my mice, but at the same time, I want them to have things to play with and chew on and crawl on...so I gave them a few things to play with, but I'm wondering if anyone has any objections to them (like, if something has chemicals in it that could make the mice sick when they chew on it), or if anyone has any other 'unconventional' (read: dirt cheap) toys they let their mice play with?

Here's what I have so far:
yarn tied to parts of the cages (it's a wire cage, Turbine likes to crawl on it and chew the knots)
toilet paper tube
pieces of a torn up shirt
q-tips
stuffing (you know, like for stuffed animals)
cardboard
the cardboard box they came home in, with a hole cut in the side and taped to the side of their cage (they've actually already chewed a hole in that, so now they've got a window, but they're not about to escape out of it; it's about a six foot fall and none of them are brave enough to jump)

[Nibbler]

paper toilet tubes with toilet paper or paper towel in them is a toy they can use and hide a treat inside it

[Vladina]

Yes, scraps of cloth, toilet paper tubes and paper towel rolls cut up into smaller tubes sound great, but I am not sure about Q-tips. Hopefully some mouse veterans on the forum may chime in about whether those are safe or not. Stuffing from stuffed animals sounds fun also, but make sure any type of fluff or stuffing is not the thready kind that can accidentally get wrapped around a little mouse foot/toe.