Canon irc1021i how to print random size paper

Random size paper? As in the printer will just decide what size to use based on what it feels like?

Maybe you mean "Custom" size.

First read the manual to check what paper size it will print on, if you try a size too small it will probably jam the printer.

Use manual feed, move the slider to fit the paper. In the drivers, select the right size for the card. If you don't have the right options, try a newer driver if there is one.