I always roll my on tubes, especially for MMT's. I use regular index cards and a glue stick (or sometimes white or yellow glue). I used to roll them around spent casings but had some that shrunk too small as the glue dried. I now use .75 and 1 inch dowels as mandrels. Masking tape is required for a good friction fit but they work like a charm.

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Trash Can Rocketry