Re: KaM and K'nex?
I liked K'nex, but I never got very many of them since I preferred legos. Your projects are very impressive, indeed.
But the most impressive thing I see is that you are from the United States! Someday, you'll have to tell me the story of how you were introduced to KaM

My mother used to bring my sister and I to what we call "yard sales" in the US often (not sure if that's a familiar term for you all) (where you are allowed to post signs around your neighborhood with your address mentioning that you were selling household items at your house). My sister was into the middle age time period, and actually she wanted the game as soon as she saw and read the description on the box (I actually want NOT interested just by looking at it, but I had no idea what it was, as I never played a strategy game before it.). I don't remember how much the guy (I'm guessing he was in his mid to late twenties) sold it to us for, but it wasn't much. He said it was a great game (but selling it at most 1 year after the original release date made me wonder if he really liked it). Anyway, my sister ended up not having patience for it, but when I played it for the first time by myself, I was hooked.
I don't know K'nex at all, but nice work !
I'd like to see the plans(I made the Trebuchet from AoE2 which you could pack and unpack. It could take a 2 pound (about 1 kilogram) counterweight easily, but it did fire a decent sized projectile 35 feet (about 10.5 meters) with a 5 pound (about 2.25 kilogram) counterweight. If anyone is also an AoE2 fan and/or K'nex fan and is interested in seeing the plans (in picture form, let me know).
UPDATE in 2021. I made a post about this on Reddit and have replaced the past links with this Imgur post. In it I explain things better.
From the Age of Empires 2 game,
I also made the "scorpion" (similar to TPR's ballista), "bombard canon", battering ram, and siege ram out of K'nex, but sadly I didn't take pictures of them (and I hated myself for that!).
The siege ram was very strong (both its attack and its structure). For the "bombard cannon", I basically made it by using green connectors to make a "pipe", and I used a rubber band to pull to put potential energy on the K'nex ball which I put inside (god, that thing shot almost as far as the trebuchet, and I could control the aim very easily). Oh well.
What makes me an Expert isn't my skill in of itself but my desire to win big.