Traditionally rum cake is made in a Bundt pan. If you do not have a Bundt cake pan you can try making the cake in a pan that has a 12-cup capacity such as a 10×2.5 inch springform pan or a 9-inch tube pan. I have not tested the bake time for these pans so you will want to start checking on the cake about 30 minutes in to make sure it's not burning.