Try making one with a squeeze
bulb, medical tubing and a
ground down blade. If it's sharp enouth to cut cheese it's probably too sharp for the actor. ( you can quote me on that) A budy of mine is recommeding a fish tank hose, which will work just a s well aas the medical tubing. Also check Prop master's
hand book or Tom Savini's "Grand illusion"
book one or
book two.
When I did FX's for Todd we did a thin homade blood that was mostly water kero and Coloring an then we poured it into the handle of the knife,( which was a homade Sqeeze
bulb. I'm on the wrong computer to
send you drafts of what the knife looked like but there was a
snap together feature that was pretty cool. Laso remeber that your tube doesn't have to streach to the top of the knife it, it can be located at the
base and then th actor can drag blood across with the incredibly dull peice of metal.
good luck bo