You can only use their ink. You make the stamp, ink the stamp with their ink, that will last for about fifty uses of the stamp, then you re-ink the stamp.
Other inks do not work. You cannot use the same stamp with different colored inks. You cannot use embossing ink with the stamp (although the ink they use is pigment, which you can use with embossing powder, but what if you just want a clear stamp and colored embossing powder?) I hate products that have proprietary consumables
I've still not made a stamp with it. I'll do that today. I need to make more than I'd planned on, little holly branches with berries, for left and right corners. My own personal sentiment since space is tight in the cards I'm going to be making and a stamp will have even spacing, not scrawling chicken scratching that scrunches together at the end.
I got the Mint at a really good price. And I have a lot of their ink, I bought a bunch at another website when I got the Mint.
But I think, even though it's more work and probably takes more time, my go to stamp maker will be the Imagepac Stampmaker. Those stamps are much more versatile.