Here is a visual guide of how I ship hatchling and yearling tortoises. The small plastic containers I use have holes for breathing. I also make sure they are high enough to allow the tortoise to right itself in the container if the box should end up upside down.
For a larger tortoise I would use a small box inside instead of the plastic container. The box again should be high enough to allow the tortoise to right itself. I also don't like using bags, socks, pillowcases just for this reason. In a bag they can't right themselves if they get upside down.
For a turtle I would just make the paper towel damp. For a larger turtle I would use a larger plastic container.
For a larger tortoise I would use a small box inside instead of the plastic container. The box again should be high enough to allow the tortoise to right itself. I also don't like using bags, socks, pillowcases just for this reason. In a bag they can't right themselves if they get upside down.
For a turtle I would just make the paper towel damp. For a larger turtle I would use a larger plastic container.