Can I brush the epoxy on instead of pouring it?

Only as the seal coat. UltraClear Bar & Table Top Epoxy is applied in two stages: a thin seal coat that you brush on with a paint brush, and a flood coat that you pour on and let self-level to 1/8" thick. The brushed-on coat is not smooth and is not suitable as a final coat. It is a priming step that seals a porous surface so the flood coat doesn't bubble. The poured flood coat is what gives you the seamless, glass-like finish and a full moisture barrier, so it is always needed. A brushed seal coat by itself will not waterproof a surface.

For the seal coat, mix no more than 1 quart at a time (1 pint resin + 1 pint hardener), stir by hand for 2 to 3 minutes, and brush it over the surface in a thin, even layer, mixing a fresh quart to continue where you left off. One gallon covers about 48 sq. ft. as a seal coat. Wait 4 to 6 hours, then pour the flood coat in batches of up to 1 gallon and let it level on its own; don't spread it around.

If a poured coat isn't an option, such as stiffening the back of a flexible sculpture, the epoxy can be brushed on, but test on a small piece first. You won't get the seamless finish of a flood coat. For table legs and undersides, use a spray-on oil-based polyurethane instead.

Instructions: https://cdn.shopify.com/s/files/1/0320/7168/0140/files/Epoxy-Instructions.pdf?v=1616443869