Once again, please forgive me if this is answered somewhere, the search function really doesn't like my search terms.

Is there a way to attach, project or connect a 2D object to one of inkscapes 3D boxes?

prkos, I know you've done similar things, which lead me to live path effects but I'm not entirely sure how to apply this in two dimensions, matching the 2D source to the 3D/perspective of one side of a box.

Is there a tutorial for this, or am I just too thick to work out the live path effects to accomplish this goal?

You need to use Perspective effect, here's some info http://tavmjong.free.fr/INKSCAPE/MANUAL ... erspective

In 0.46 you need to draw the perspective frame, it might be important to draw the bottom left node first. Then select both the object and the frame and do Effects > Modify path > Perspective

To draw a nice frame you can use 3D box, draw one you like and then with snapping to nodes on draw (using Bezier tool) the 4 node frame (it will snap to box corners.) You have to do it for each box side separately, and for each object probably (in that case you have to draw different frames for each object if the objects are of different sizes).

The development builds can apply those effects to groups but I haven't tested it much. Also you can find the Perspective effect in LPEs in dev build so you can edit it live on screen.