Choose the types of rocks that will best fit into your interior design style. For example, use one large slab and tailor the design to fit its dimensions, or incorporate smaller decorative rocks into the plans. Options include river rocks, or other polished and multicolored stones.
Decide on whether you will keep the grates natural or dress them up. For example, for an industrial design, only clean and polish the grates. For a more colorful contemporary style, look into metal paints to change the color of the grates.
Consider the base of the table in your tabletop design plans as well. For example, if you are welding a simple metal base for a monochromatic kitchen, choose rocks in the hues of grays and blacks to complement the metal. If you are pairing the grates and rocks with a wooden base, add rocks in oranges and reds that help define that contrast.
Study the sturdiness of the grates themselves. Make sure that they are able to be welded together to create a safe enough structure to hold up the weight of the rocks. If not, additional metal elements or wooden ones may need to be added to fortify the tabletop.
Choose the finishing cover of your tabletop. For example, have a sturdy piece of thick glass cut to fit your dimensions if you plan on changing out the rocks or adding seasonal decorations to the inside of your tabletop design throughout the year.
Consider pouring a clear resin around the rocks to set them in place if you are looking for a more permanent finish to your tabletop. Cover this with glass cut to size, or finish the top layer with a couple coats of polyurethane for less maintenance.