Simple mockup ability

[mno13]

(Quick disclaimer) I'm not sure if it isn't out of scope for "VIEWER" software, but there isn't really any other simple software that does that.

Add ability to create pseudo assembly from opened files. Useful for doing quick mockups and checks if some components would fit together.

A way to simple put one imported file inside antoher and move or rotate it with simple 3d gizmo (for reference: Catia's "compass" or solid edge's "Steering wheel"). Snapping face to face or axis to axis would be nice.

Ability to do mockup from BREP (Step), Mesh and pointclouds files.

Any save or export could be simplified - mockup from only brep files could be saved as STEP, but anything else only as mesh file (JT / 3DXML would be perfect in long term).