- in a Project 3d Model ,you have to use Work Plane:
- Work Plane > Set >Pick a Plane - hover over a face of your volume and then click on it to make active .In this new Work Plane ( that can be view choosing Show -Show Work Plane) In this Work Plane you can use Snaps. Then you can choose another Work Plane and continue the process...
2. In Conceptual Mass you can use 3d Snaps

Constantin Stroescu
