Just wondering about a couple things. You said in your original post that you used 3/8" steel rod, but the measurement you gave (.124 inches) is actually about 1/8th inch; I'm guessing 3/16" would work too, right? Also, what did you use for a spring in Prototype #3? It doesn't look like a mousetrap spring.
Oh, one other question. Did you consider making these and selling them? Because you've done a brilliant job.
Keep up the good work; like the other guy said, I look forward to seeing more of your projects.
Davis