I got a 5550 when I was kid, I always liked that model, I found it fun to play with, destroy, rebuild, etc.
After my dark age, I found another one on Ebay for cheap. As I had parts for that, I modified the colors, replacing yellow/black by blue/red.
Then I found another one, so when you have two, why not three? It got green parts. I bought parts on bricklink for that, making a blue/darkgrey and a green/red.
Recently I eventually found a fourth one, making it red/darkgrey, with orange replacing darkgrey on the blue one.
The 5581 "Magic Flash" seems harder to find, I only got one.
My original 5550 is actually the blue one, the one in original colors is the third one that I got and that I kept as it is, since it was in nearly mint state (unlike mine, since I played a lot with it : )
I have to order parts, I am missing 1x1 orange plates (I used round ones) and I cheated for some green parts.
I do not know yet which color selection I'll do for the next one, not all parts exist in all colors (I'd like rare colors like purple etc.)
Maybe I should try to replace the white by something else too...
edit: fixed link for new pic location
Edited by antp, 22 September 2013 - 03:49 PM.