Easy to make, cheap and lasts forever!
I have many mascaras laying around, because it took some time to find the best one for me. The mascara I used for this project was a cheap, no-name brand, and the brush was very clumpy
So get your mascara, and put it in a mug of hot water. (2 minutes in microwave) and wait a couple of minutes
once you feel your mascara tube is empty, put a tiny bit of vaseline in your pot. Remember: You can always put more to it, but never can get the excess out. Mix in the vaseline. If you feel it's good, try it out.
And done! If it dries out in the future for some reason just put some more vaseline to it!
Get the mascara out of the water and get the brush out. If you're lucky you can pour it in your pot, but if you're not that lucky you have to shake it and beat it and all that stuff to get the paint out of it :D