It's good to go over your things and figure out what can be used up as-is, and what would serve you better after a bit of repurposing. My backlog of cosmetics is an endless struggle in this regard, but I am always finding ways to make my things work. Two new stories about my so-called project pan:
I have a years-old palette of oil-based face paints. They're intended for stage makeup, but I ended up not working in the field. I wasn't sure what to do with them and didn't have the heart to throw them out; the paints themselves are in good condition despite being technically expired, and if I have hygiene concerns they're easy enough to disinfect. So, in a moment of inspiration, I decided I would use them as cream eyeshadows instead of buying some new product for the purpose.
One tiny problem... they're literally greasepaint! Which means they require setting with loose powder after application. Good thing I already own a loose powder; It was supposed to be a powder foundation, but it is not remotely the same color as my skin, especially once it oxidizes. So I might as well use it for setting my eye makeup. It mutes the colors because it's skin-toned and not translucent, but I'm fine with that. So the 'problem' ended up being a 'solution', letting me use up two products at once :)
I have bars of soap at home that I have no clue why I own. A recurring theme with the purchases I made in my 20s... I guess I was going through some experimentation and self-exploration at the time.
In any case, I do not use soap bars to wash myself, and neither does my partner. But after I tried to create a makeup look with the aforementioned greasepaints, I found that my regular liquid soaps just did not dissolve the material from the brush, no matter how many times I applied it! I was desperate to clean my brush before the product crusts up the bristles, so I took one of the bars and gave it my best shot. To my immense relief, it worked :) so now I know what to use for cleaning my makeup brushes (they're all synthetic, so no need for a special brush shampoo either way).
After I'm done with my face paints and have physical room in my life for a new eye product, I'll buy a palette of powder eyeshadows from the same company, because I already spotted something in their product line that would fit my needs. But that is for later, much much later.