man, I ruined all my Transformers as a kid, the old-school die-cast metal ones. Had probably 20-30 of them, lot of the big ones too like Optimus Prime, the Constructicons, Megatron, Galvatron, all the decepticon jets, etc.
Anywise, I got bored one summer when I was probably 12 or 13 and decided to take them ALL apart and build 1 mega-robot. Unscrewed every screw in every transformer I had. Those things had like 20-30 screws apiece, all different sizes. Once I got them all apart I realized the error of my ways, and I couldn't put ANY of them back together, you needed a damn engineering blueprint or something to do it.
Ruined them all, had to throw away 3 full size grocery bags full of transformer legs, arms, torsos, heads, and random parts. My parents were pissed.
I had this to fall back on though:
(I was a fairly spoiled, only child)