There are a few ways to encase the head in pantyhose. The simplest is to cut one of the legs off a pair of pantyhose and use that to encase the head. My favorite method is as follows:
1. take a pair of pantyhose and cut one of the pantyhose legs off this will be one of the holes for one arm.
2. Cut a hole directly opposite the leg you cut off This is for your other arm to go through.
When you put the pantyhose on, your head will go into the remaining pantyhose leg and your arms will go in the holes you created. The panty part of the hose will fit around your chest. Depending on the size of the person you may need large size pantyhose, maybe up to 7X.