Computer case protection wrap

You could use any kind of heat-shrinkable wrap such as that used in the food service industry.  However, you should advise the recipient that the wrap is only for protection while shipping.  The metal case transmits a significant amount of the heat generated inside into the environment and if the wrap were left on the only cooling would be through the power supply fan.

I need something that can handle scratches. sometimes I put some computers together and they scratch each other.

Use cardboard separators and then plastic-wrap around the separators.

I need something easy that takes a minute to wrap the computer . and easy to peel after

bubble plastic sheets maybe?
or isomo sheets or boxes - or glue a box together from the sheets

Usually i ship my computers on boxes larger than the case...i use bubble plastic to cover the case i wrap it at least 2-3 times..then large pieces of hard foam  to secure it inside the box and that's it...i always get feedback about great packaging and excellent condition...
Remember to pack everything that is not perfectly secured (GPU,HDD,RAM) to separate packing...