backfilling Airbrush - Holes in nozzle?

[hoary salmon]

Hi, im learning to airbrush and have been taught about backfill/back flushing.

does anyone have any tips on how I can more easily backfill my airbrush? The nozzle guard has lots of holes in it. So its difficult to cover it with my finger.

[narrow spear]

you can use some kind of cap to block it, i do it myself, just bought it in airbrush store for less then dollar