The Technodrome actually looked bigger when looking at it from the inside than from the outside. Yes, it was big, but it seemed bigger on the inside. With all those different rooms that creators came up over the course of the show, I always imagined that it was HUGE.
It's too bad I can't build a full-size replica with all those rooms from the cartoon. It would be awesome just to walk around and explore all those rooms, tinker with all the different machines, and summon all sorts of dimensions with the Technodrome's portal.
I can always dream, though . . .
"It's the Turtles!"
"My, how they've grown!"
Shredder and Rocksteady, from "Cyber-Turtles"