The idea here is that a coke can, once completely dry, could provide both lightweight waterproof storage for tinder and lighting , and also be an item to help structure the fire layout to provide proper draft and heat containment, . After the can is dry you could stuff in some matches and cotton lint or vaseline balls, maybe a magneium stick. Maybe an obviously small candle. Some items may need wrapping. Then duct tape the hole When it came time to use, open with a knife.
How exactly I would use the can to structure the fire is an open question.