Psst - your not supposed to give away secrets.
Now that the cat (crane) is out of the bag I can feely admit a local company left one over night in my back yard and I zapped it with my super duper reducer ray gun and installed it as an accessory to Gmax (using a crowbar of course - it didn't want to fit).
You found me out - Curses - foiled again.
In reality my secrets are:
1. Lots of practice.
2. Lots of time.
3. A large library of reusable subassemblies, parts, sections, and so on. I don't have to re-invent the wheel every time I start a new bridge (I made 6 yesterday).
Ben
