"You know, I don't quite understand offering rings during casual conversation, but I'll take it. I figured this one out in an experiment in my mechanical engineering class at Cambridge, and refined it in various ways since then."

"And what've you been doing with it since?" She offers another ring.

"Some doctor friends of mine found it useful for seeing inside the body. Knowledge magic kind of obviates that. They also used it for structural analysis, checking if damaged buildings were safe to enter, looking for flaws in wood timbers and steel... That sort of thing. I was thinking about using an analytical engine or computer to refine the output, make it easier to read. I could only tell about your door because I have experience with it, a layperson would not have been able to find it, I think."

"I bet this isn't the only invention you've brought to Har. Want to take the time to tell me about anything else I might want, since you're here anyway?"

"Certainly!"

He can go down his whole list, sales-pitch style, including half a sentence hinting at the operating principle for each device.

"Do you even have time to use any of these? Or make enough of them to sell everyone who wants one? It seems like you'd have more time for inventing if you just sold the blueprints."

"That's definitely a possibility! I might even go that route! Inventing is more fun than salesmanship! But for now, I have them, I put quite a bit of work into them, and I need money but not urgently. So the offer for the blueprints would have to be pretty good, to be worth handing off the work I put into them."

"It's not just these. We could come to a deal once and then next time you come to me with something about as useful and I give you about as much and you never have to find a buyer again. So. How's 14976 rings?"

He does some mental math, converting it to pounds. It's not a bad payday. However, on the general principle that you should always negotiate, "...No, that's not really enough. Perhaps if this were a barely-functioning prototype it would be, but given the amount of work I've put in and the usefulness of this device I should expect, er," He slips into English, "Twenty five thousand?"

She haggles.

He backs down fairly easily, the final amount isn't that much higher than her initial offer.

"It's a deal. Well, I'll actually have to go fetch all my notes and touch up some of the documentation - er, do you have a warded box I can put them in? I've just been keeping them indoors."

"Yeah, it's around here somewhere... yeah, here, no charge if you give it back when you're done."

"Thank you. Should I go now, or would you like to talk about the ultrasonic scanner a bit more before I do? No more careful answers. You're getting the blueprints anyway. Oh, and you can have this one for cost of parts, that's about, er, 144."

"Might as well bring it now. Want half the rings before you go?"

"No need, no need. This is civilized business after all. I'll be off, then, and back as soon as possible this afternoon."

Foreigners are so weird.

She's still at her office in the afternoon.

And he's back with her box of documents. "Hello again. Your name is Nimo Saramel, correct? I'm Curtis Warden, I realized on the way back that I never properly introduced myself." He presents his hand for a handshake.

She shakes his hand.

"Yeah, that's my name. You come back next time you invent something, okay?"

"I have more inventions now. And... You don't want, say, an explanation of how to efficiently build it, or the nuances in using it?"

"That would be good. That won't cost me extra?"

"Not unless you want to monopolize me for hours, no. I was assuming an hour or two of consulting on design was included with the blueprints!"

"Oh! Then have a seat, get comfortable. Would you like some greens?"

"And besides, you're 'in' on the technical secrets now, so you might have an interesting new perspective - and it'll be fun. Sure, thank you. Er, do you know if all your greens are alright for humans to eat?"

"I think so but I'm not sure, can you have arugula and alfalfa?"

"Yes, I recognize those. We don't find them tasty necessarily, but they're quite edible. Usually we would add other things, but I'm hardly complaining."

He starts unpacking blueprints and sketches. They're kind of disorganized, with a patch-job unifying them into one sensible document.