Confetti Cannon

Placing it is easy. Aiming it is the fiddly part. You nudge the barrel round one notch at a time with the activate key, it will not point at the floor, and there is a limited set of angles, so work out where the burst should go before you build scenery around it.

Firing by hand costs nothing, since the torch is only the trigger and never gets used up. The catch is that hand firing runs off a single cooldown shared by every cannon in the world, so lining up ten of them does not give you ten times the confetti. Wiring is the better answer for a display, and depending on which side the signal comes in from, the same wire can be made to swivel the cannon instead of firing it.

None of it does damage. Confetti passes straight through anything standing in the way, so this is party furniture with a trigger, not a trap.