Been thinking about Kana and Bruno if they were in the original show again (Insert shameless plug of my Kana headcanons) and ended up thinking about their bases.
Bruno is simple enough. I'd make him a bobber caboose since they tended to 'bob' along the tracks, and that reminded me of the way he stims by rocking in AEG. And like every other American in the series, he'd have buffers and screw links.
But Kana's a bit of a weird one. I thought about having her be a 0 series shinkansen, but I don't like how big that would make her. But then I thought about the fact that I'd have her at the Earl's railway museum, and since this is the Earl we're talking about, I feel like that gives me a little leeway to be a little weird.
So let's say Sir Robert commissions a Japanese manufacturer to build him a one of a kind electric engine for his museum, and Kana is the result of that. She wouldn't be as big as Gordon or Caitlin, but not as small as Nia or Thomas. But despite her somewhat small size, she's one of the faster engines on the island, leading to the workmen jokingly calling her the 'Pocket Rocket.'