Don't know if you can display C2 objects on Q3D canvas .....
you can but in the plugin its named front/inside rendering which is more like having a layer above and make its bg transparent... and when u move around the 3d canvas... well the 2d canvas items dont move... they are like the HUD stuck on the monitor ..however he did a work around it and added a 3d sprite... which is like a normal 2d sprite... just behaves as a3d object on all 3 axes... using them isn't good ... their similar with the phong balls.. if you solve that wold be awesome haha
Edited: yea i see now, regarding the phong balls why they heavy ..seen ur post to late