Need HELP!!

[BryanS]

I am trying to make a pattern for a puppet head.
the puppets face and head is the same size as my hand
The pattern needs to be in 2 seperate peices then sewn together right down the center. I have made one pattern and cut it out but when I sew it together it is to small for my hand and arm to fit in it . It does not fit around the mouth plates either its too small

My question is,

How much bigger do I have to make the pattern to allow for the seam, and to cover just around the inside of the mouth plates to fit my hand like a mit when I sew the 2 peices together?

Please if someone could help I would appreciate any suggestions.

 

[Buck-Beaver]

Check out this "blue boy" pattern, it might be helpful.