Tub of pot?

Hey guys, I'm starting my first indoor grow and looks like I'm going to utilize my extra bathroom . I was going to germ my seeds in small pots first but was wondering if after there ready to transplant if I could just fill my tub or similar size container with my media and plant all my plants together in one big "flat" so to speak? It's a big oval garden tub I was thinking of only 3-4 plants. Is this something that's done? I no maybe not the tub part. But the one big container? Multiple plants? Thanks for your help