Jim, I think Sullivan makes a decent 1 oz tank shaped like a cylinder. Just go with a solid 3/32" brass tube in the tank to deliver fuel. Sullivan also makes the best small silicone fuel line. It helps to have a 2 ounce syringe with a hunk of 3/32" brass tubing sticking out of the syringes' tip to make refueling easier.

BTW, to keep a round tank from rolling inside the plane, pack it in there tightly with foam. It will also prevent fuel foaming.