Let's build a boat in Onshape (well, the basics of the hull surfaces at least) 

Thanks for the note - yes I guess this demonstrates the power of custom features: that users or developers (internal or external) can experiment, get early feedback, iterate... and make decisions about whether it lives on as a custom feature (which is a perfectly valid outcome) or becomes part of the native code base.

While that's not the message I was trying to portray, I apologize if that's what came across to you. For the vast majority of mechanical CAD users, the topic I was covering is not so relevant and the complication of projected or intersected curve may not indeed be of any downstream consequence. However as Onshape grows, and the customer base expands, there *are* indeed people to whom we are talking, learning from, and reacting to, that this topic is of great importance. So: 1. it's important to understand that the foundations of Onshape do not preclude such advanced modeling. Under the covers is a fully capable NURBS modeler. It is up to us to decide how and when to present this via features in the UI. 2. FeatureScript is a huge differentiator for Onshape, in that it is the language we have developed ourselves to create the features we ship as part of the standard package. If anyone is interested, the standard library is publicly viewable. If you want to see how we use FeatureScript to deliver things like loft or patterns, or in fact anything in the part studio, then you can do so. The important aspect here is that it allows us to prototype new approaches on top of the foundational capabilities, for example the approximateSpline function has been in the std library for some time now, and opCreateBSplineCurve even longer. With the latter you can completely take control over everything in the NURBS curve you are building. 3. for advanced users, understanding FeatureScript is extremely useful (and I recommend it!) as it helps to know what the part studio is doing. This can lead to a better appreciation of how to approach regular modeling tasks, optimize for performance, and more.. Even if you don't intend to write you own custom features. So I'd prefer the take away to be much more optimistic: that we are rapidly building an extremely powerful application (Onshape) which is applicable to more and more users and use-cases. Along the way, and before we commit to shipping certain things, we are able to experiment, collaborate, iterate, and improve. There is ample evidence of this in all aspects of Onshape, and particularly with surface tools. The last two years have seen unprecedented expansion across wireframe/surface modeling, & diagnostics, with much more to come.

@@gregbrown-onshape7555 Thanks Greg for your considered reply, I appreciate the effort. I should explain I've been using Onshape for about 5 years, and have been a subscriber to your channel for ages (not sure exactly, but have learnt a lot from your videos). I absolutely love the product, and you'll get no argument from me on the unique extensibility offered by FeatureScript. Normally, I find the message in your videos clear and straightforward (I especially like your face-blend tutorial, clear, concise and comprehensive), but I found this one troubling, even after re-watching. Anyway, I won't waste your time by labouring the point, just wanted to say thank you for taking the time to reply. Cheers

Yes, if you have cross sections then indeed a loft feature could be used