We actually use our large dutch oven

For a full packer brisket?

Go to a restaurant supply store (or online) and get a steam tray or "hotel pan." Full size, not the half size ones. Should only be about $15 and fits a brisket and veggies perfectly.

I use the same one I use for a turkey. If you dont have one big enough you can make brisket in those aluminum pans they sell at the supermarket. However, put the whole thing onto a big sheet pan so you will be able to pick it up. the aluminum pans can be flimsy with the weight of a brisket.

Looking for a large roasting pan that can fit brisket plus vegetables. Any recommendations? I think what I have is too small.