The casting is done with mold blocks. Sizing if needed is accomplished with a lube and size dies. It depends what you want to cast? In the case of plinking loads follow the other post aluminum molds and Alox tumble lube. Wheel weights will suffice for this type of shooting.
If you intend to mold rifle bullets quality steel mold blocks and gas checks would be in order. Cast bullets running above 1,500 FPS need more attention. The secret is to slug the bores you are casting for and size bullets .001" above bore size. If you are casting for Micro-Groove you may need as much as .004" above bore size. Get the Lyman Cast Bullet Guide and study alloys such as Linotype, Monotype, Sterotype, Foundry lead and BHN factors.