Possible Clues:

• Pupa's protective case
• Make a pup a twice as firm on this
• Perhaps make a pup a double firm on the end
• Twice as firm on something that may have a beautiful outcome
• Cover made of silk
• Perhaps a pup, a couple of firms on the end
• Twice as firm on where it makes pup a place there
• Protective cover of silkworms, etc
• For a pup, a place that's twice as firm and covering
• This would make a pupa a couple of times as firm on this