Thanks so much for this! It's amazing and took way less time than i thought.
For those having trouble snipping the end off the screw, i used these threaded rods instead.
No snipping or additional sanding required, but they are a bit long so you have to use a longer section of tubing. I screwed the rod into on of my needles and then used the grippy pad thing (cut in half) that comes with the set to hold both the tubing and the needle to screw the tubing on. It gets a little tough to get the tubing on the further the rod goes in, but it is possible. There does seem to be some variation in the depth of the hole needle to needle, so check two or three of them to make sure there is no gap between the needle and the tubing.
The screws linked in the original post are steel which is very very hard to cut with most tools that are also usually steel. You may have better luck with a brass screw:
Brass is a softer metal but still pretty hard and probably more than sturdy enough for knitting needles. You should be able to cut it with steel. If you have little wire snippers for beading or something, that may still not work.
Hope this helps!