You can make Boston brown bread in a loaf pan or in various size
cans. A 1-lb coffee can is approximately 4" in diameter and 6" high.
In my pantry I have a 30 oz can of pumpkin pie filling that is 4" in
diameter and about 4" tall. Grab your tape measure and head for the
big sizes aisle in your grocery store.
Here are some recipe links:
Oven steamed in 1 quart pudding mold or 1 lb coffee can:
http://www.epicurious.com/recipes/food/views/boston-brown-bread-104112
Loaf pan in oven or coffee can on the stovetop:
http://www.simplyrecipes.com/recipes/boston_brown_bread/
Oven using 26.5 oz cans:
http://www.foodnetwork.com/recipes/alton-brown/boston-brown-bread-recipe.html
Stovetop in 15.5 oz cans:
https://newengland.com/today/food/cooking-advice/step-by-step-recipes/steamed-boston-brown-bread-the-small-loaf-edition/
Oven in loaf pan:
http://www.kingarthurflour.com/recipes/boston-brown-bread-in-a-loaf-pan
Jeff