How about making some more pop up target activators, and chaining them,so that each one trips the next. Perhaps 4 in a row. Pop, pop, pop, pop, gone. I can make some a bit cheaper without pipe endcaps :-)
Small swinging platform (like the big one at Rotorua) -- my old one is still around by Range 1, although I think the weather has rooted it, but it would be easy to rebuild. I did build a spring based rocky platform, but for some reason it never worked as well for me...
Some of our newer members haven't seen air operated windows, but perhaps tripped by a light beam this time.
Completely hidden stage, nothing visible, no target count known...