I trap/sell my own tanned Beaver for string silencers and such. I use a big chunk of the back hide/hair section where the under hair is the most dense. Then I shave it down to about 1/4"-3/8" depending on how it performs, leaving a nice flat spongy matt of fur on my arrow shelf. I love it, and I get great arrow launch off of Beaver versus anything else I've tried.
Last tip, I use double sided tape the heavy duty 3M brand for sticking my Beaver rest to my arrow shelf, and so far I haven't had any issues with it. I then use a piece of mole skin, or felt on the cut out above the riser shelf to deaden any arrow contact.