"The idea would be that, initially, I commission a few designs from you. I'd explain what I want, maybe give some extra requirements such as a price goal. Then you go about designing that with the tools you are given, which would probably expand as you prove you're up to snuff. At least initially though, you'd keep things 'theoretical', and not work with physical prototypes. If possible you'll work together with me or whoever is commissioning the design to maximise work efficiency, or give weekly progress reports. Then in the end I'll review your work, and we can decide if it's within design parameters. If yes, we test it in live conditions, and if it still holds up, we put it into production.
Once you've proven to be capable and reliable, you might also get the chance to work on personal projects, basically meaning you'd get to design whatever, as long as it helps us. In return for your efforts, you get more luxuries, privileges and freedom, or something else should you think of something. What you get exactly would probably be negotiated case-by-case. Of course, there'd be substantial safety measures to act as insurance. Can't just ignore why you were put here initially, I'm sure you understand. In the end, we might ask of you to do some artifact testing, though that's in the far future.
And, just to be complete here, should you try to doublecross us or do anything funny, these new privileges can be taken away again, and involuntary volunteering for the Doc's experiments might be put on the table again, but I sincerely do not wish that to happen. You are far more valuable to us happy and productive than as a prisoner in a bare cell or a test subject.
So, do these conditions sound agreeable to you? If yes, we can move on to your first assignement, getting you some tools to work with, and deciding what you'll be getting for it."