"Do you happen to know if controlled electricity works at home?" the older woman asks the younger one after a while.

"Controlled how, like, single-target?"

"No, like, used for lighting."

"I've never heard of that."

"I have some engineering background if that's something you want to bring home, it's possible to learn from books but a little harder."

He has a suddenly rapt audience. 

...gosh, okay. "My education was spotty on how you actually acquire raw materials and render them into the useful forms, because I can just make stuff and was taught with that in mind, but I can teach you how it works." He will start with a basic chemical battery and a lightbulb.

They are not notably brighter than average, and they clearly have approximately zero science education, but they're very very focused, and seem to be taking entirely seriously the possibility that they'll spend their natural lives here studying engineering. 

If they want to spend their natural lives here studying engineering Cam will accommodate this as long as people from other worlds can still get in the door sometimes. He'll buy them rooms if they want and don't object too much to counterfeit.

They want the door closed; that means their world will be paused while they learn engineering. They object to counterfeit of fiat currency but not to Cam producing items of value which Bar will accept as currency.

Cam will switch to paying Bar in assorted corundum.

They introduce themselves, eventually, a couple days later, for real - the younger woman is named Araya and the other woman is named Isavel. "Ideally we'd have more people in here, but I don't think Iomedae can work with the door closed, or they'd have come in already, and I don't know anyone else who's close - we're far from the areas the church normally operates in."

"...I mean, if you want to hold the door I can pay for your room. I guess I could also make a shuttle without myself leaving the bar, and pilot it remotely to whoever you wanted to pick up?"

"It's not really safe to leave open for days. ...what's a shuttle? Wouldn't it need electricity? We don't have that at home."

"A fast flying vehicle and I would make it with a fully charged battery. It can probably get any one place on the planet and back in less than a day unless your planet is huge or something, but if you want lots of trips, it'd take days. I could... buy the inn for you?"

"....maybe we could do that. I guess it wouldn't look that suspicious, really - and luckily we're on this side of the border -"

"Is the innkeeper likely to take gemstones or should I sell some to Bar for gold minted like yours?"

"They'll want coin, there's probably no one in this town who can check gemstones to see if they're real."

Cam sells Bar some rocks until he has a very large sack of platinum and gold for them to buy the inn with.

"We should do the shuttle at the same time, probably? So we're not holding the door twice - will the shuttle be noticeable to magic -"

"I mean, it's not going to be invisible. It's going to be a large metal object that flies through the air. It's not super loud and it's not itself magical."

They exchange concerned glances. "...could it be invisible?"

"...I can't make it that way but I could make it very high up? It will still have to land to collect passengers..."

"There aren't Chelish spies in Lastwall, but this place is going to be crawling with them. It's all right if it has to land when it gets there. - also probably it shouldn't collect them, they'll be suspicious, it should just have a note telling them where to Teleport to."

"If it's just going to carry a note it can be much much smaller," he gestures a squirrel-sized shape.

" - oh, that'll be safer. Even if they notice it they won't think it's something important. Yes, something like that - how does it fly without magic -"

"The little kind is very fast spinning things, like you know those seeds that spin when they fall, if you do one of those that's powered so it can spin faster it goes up instead of just falling more slowly."