Tried credit cards tried brushes hated both.

Use a foam roller 2 to 3 inches wide you can really work the epoxy [ never polyester ] resin in even using the lightest cloth.

It is also MUCH FASTER. I find I use two coats the first laminating resin the second finishing resin and still need to fill pinholes.

If you have thick resin do not be afraid to warm it up after mixing it will thin out and flow better. N.B. It also sets faster. You can use an alcohol thinner or meths but I have had problems so I use thin warm resin.

ALWAYS wear protective gloves and ALWAYS wet sand epoxy and dispose of the contaminated water and cloth or tissue carefully. Never blow off or allow the dust to dry out. The dust is nasty stuff and is a cumulative allergic irritant.