Hello cutty.....After skinning it out I would leave it as a raw material.When making a handle wrap for a paticular bow I would make a stencil duplicate first that fits,like in the build-a-long that [buddy] has shown using masking tape.
I would also after duplicating that form onto your raw beaver tail I would contact cement a layer of thin deer leather onto that or at least onto the the edges to be sewn because raw beaver tail is very thin material.
From there glue it to your handle and sew it up.I use contact cement myself.