I made this as a prop for a stage production. The handle and blade are hollow. The handle prints with no supports and the blade only needs supports under the nipple. The back of the blade has a nipple where you can attach surgical tubing. Then handle has a hole on the top near the back so you can run the surgical tubing up your sleeve and connect it to a syringe or maybe a pump. Fill it with stage blood and squeeze the syringe as you drag the blade across someone's throat. The blood will come out of the opening hidden on the edge of the blade.
I used:
black latex tubing ID:6mm OD:9mm
60ml Catheter Tip Syringe