If you want to use multiple colours on your stamps, here's one way to do it: instead of using an ink pad, use markers!

Start with your acrylic stamp and one marker.  I've used Tulip red on a heart.  Colour where you want that shade to go.




Then colour with your second (brown) and third (pink) colours.


Then, when you're ready to stamp, there's one more thing to do: HUFF!  That's right, gently "huff" a breath on the stamp to re-activate the ink with the moisture in your breath.

Then stamp on your cardstock.

It may take a little practice but it's an easy and economical way to add some multiple colours to your stamping.