Last time we tried to make a blood burst effect with a fishing line and a washer. This time we decided to try other ways like using pyrotechnics. Ingredients are still very cheap: a piece of wood (for protection), a petard, a needle (to make a hole in the petard), a nichrome filament (to use as a detonator), a wire and some batteries.
It worked nicely but we should use much less blood next time.