Do not throw away the remains of acrylic paint mixtures on the pallet
If you want to reuse the paint residues (acrylic) after painting - simply use a glass plate (also plastic plate goes) as a palette. Once the palette is full and also dry - simply peel off the color mix - trim if necessary and use on a new image.
Thus, e.g. a great collage - the easiest way is when the palette is previously painted with an acrylic gloss gel. Then it can be easily removed.
Other tip:
If I have paint (acrylic) left over after painting - then I spread them colorfully or skillfully on a large piece of brown paper (size is variable as needed or space).
For larger pieces, I attach it to a wall and have it always ready to paint.
Every time a little more is added.
If the paper is then fully painted or m.E. finished, I have self-made wrapping paper.
Looks always great and is also a bit more personal for the recipient.
Good color is expensive and so it is not wasted - if you have again pressed too much from the tube / bottle.