Need Help Making Ambiguous Shapes Illusion

I’m attempting to learn how to use Shapr3D to design custom “ambiguous shape” illusions in the style of Kokichi Sugihara.

Before I do any custom ones, I just want to make sure I know what tools to use to do a basic one, so I’m following this tutorial which is meant for Fusion360 and my hope is to translate the technique to Shapr3D’s capabilities.

Using Shapr3D instead of Fusion360, I was able to follow along up until about the 8:30 mark here: How to Make Ambiguous Shapes // Fusion 360 Tutorial - YouTube

Sketching the circle and triangle outlines was no problem, sketching the lines coming down at an angle was no problem, and the sweep tool worked, but what tool should I use to get that curve?

I tried performing an intersection, and that produced a body with which the curve I want could be selected, but there doesn’t seem to be any way that I know of to remove the solid body and extract/project just the curve so that it could be joined with the inner part and extruded downward. If I select the curve and project it, it projects onto a flat sketch, but this is not what I want–the curve has 3 dimensions to it, and the height is really what makes the illusion work.

Any help would be appreciated! I’m starting to think it’s not possible :open_mouth: