I would suggest that you buy the bubble rap, remove the CPU and wrap the MB up several times and then tape the ends witht the shipping tape. Put it in a box with the pop corn, ensure that the pop corn are underneath the MB as well. As for the CUP, I would suggest useing a spounge and putting a peice top and bottom, use the bubble wrap and wrap it up, use the tape and then put i9t in the box. If you do not want to go through all of the trouble, leave the CPU on the MB.
Also the UPS or any UPS store will wrap items for you which would make them the responsible ones.....