Deer hair bugs are tough to tie. I have been tying for a while and tied trout flies for a shop during college and they are still one of the hardest flies for me to tie. One tool that makes it a little easier to tie them is a hair packer.
When it comes down to it, at least for me, the brassie packer and the bic pen work equally well. The anvil is definitely the best packer that I have used.
As you can see I still need some practice with the deer hair bugs but this little diver will hunt.