I use a large-handled X-acto knife, the kind with the burgundy handle. Drill the proper sized hole in a block of wood, insert the knife, and put the whole thing in a vise, blade up. You can probably skip the block, but I like to protect the handle from the vise. Clip the end of the quill with wire cutters to give you a "square" end and just (CAREFULLY) push the feather through the blade. It seems to me to be easier to control the feather going through the knife than it is to control the knife going through the feather.