Sure, here's a possible process for building a beautiful black epoxy river table with materials and tools for the project:

Materials:

Wood slab (preferably a hardwood like maple, walnut, or oak)
Epoxy resin and hardener
Black pigment powder
Sandpaper (grit 80, 120, 220, 320, 400, 600)
Plastic drop cloth
Mixing cups, stir sticks, and measuring tools
Blowtorch or heat gun
Router
Table legs and hardware
Tools:

Table saw or circular saw
Planer or thicknesser
Belt sander or orbital sander
Drill and screws
Process:

Start by selecting a wood slab that is the appropriate size for your desired table dimensions. A hardwood like maple, walnut, or oak is best for this project as it will be able to withstand the weight of the epoxy and provide a beautiful contrast with the black pigment.

Use a table saw or circular saw to cut the slab to the desired length and width. If necessary, use a planer or thicknesser to smooth out any rough areas or unevenness.

Sand the surface of the slab starting with grit 80 and working your way up to grit 600. This will ensure a smooth and even surface for the epoxy to adhere to.

Place a plastic drop cloth under the slab to protect your workspace. Mix the epoxy resin and hardener according to the manufacturer's instructions and add black pigment powder to achieve the desired color.

Pour the epoxy onto the center of the slab and use a stir stick to spread it evenly. Use a blowtorch or heat gun to remove any air bubbles that may have formed.

Use a router to create a river channel along the center of the slab. Be sure to leave enough space on either side of the channel for the epoxy to flow through.

Mix a second batch of epoxy and pour it into the river channel. Use a blowtorch or heat gun to remove air bubbles.

Allow the epoxy to cure for 24-48 hours, or as directed by the manufacturer.

Sand the surface of the epoxy starting with grit 80 and working your way up to grit 600. Be sure to remove any rough spots or unevenness.

Attach table legs and hardware to the bottom of the slab using a drill and screws.

Enjoy your beautiful black epoxy river table!