I did some freehand filework on the back of my Opinel #6 pocket knife
blade, using a round diamond needle file.
The knot playing cards came from ebay.
The Pugster metal bead looks like a 7 bight Turk's head knot, and will fit a
loop of ungutted paracord, so folks can just buy the bead if they've
given up on tying one, lol... :P