Perhaps the most important concrete kitchen countertop material is the mixture. The shops of home improvement are a variety of mixtures specially formulated for countertops. These mixtures are pigmented or you can customize the color dyes. Consult a specialist store for the quantity of mixture required for your project and ask for a copy of the technical data sheet of the mixing, placement and curing time, the compressive strength and other details.
The best materials to form the mold for concrete kitchen countertop are melamine, Plexiglas, steel and foam rubber. If your countertop will have rounded edges or sharp curves, the foam rubber is the best material to use. For long and not very sharp curves, Plexiglas or ammonite sealing it is easy to fold and secure with wooden blocks. If you go to spray the surface of the counter, you can do it using cheap stuff.
When you put a concrete kitchen countertop where it will remain, it must heal slowly and evenly, using a curing cover helps keep the wet concrete while it heals. Use a cover that does not stain the concrete. The woven fabric is inorganic, so does not stain or adhere to the concrete. Talk to a specialist store home improvement on the finish you want for the counter.