I've imported a 3d bucket created in photoshop into a composition, How do I go about filling sed bucket with liquid which then could empty. I can't figure out how to interact a 'solid' with the 3d object.
The liquid I wish to have in the bucket ready to empty is paint, so the liquid would be very thick and wouldn't need much partical interaction, but mainly a shaded flowing solid.
Is there any suggestions?
If you want something convincing, you'll need to do it in a genuine 3D package.
But within AE, you may get a nice animated replication of fluid with a combination of some clever mask animations (for the main shape and flow of the fluid) combined with additional particle layers. Take a look at the CC Mr Mercury plugin, which is a fluid/meta-particle simulator supplied out of the box.
Use animated masks and apply the Bevel&Extrude Layer style or check the Mettle tutorial on how to fake streams of liquid using Freeform/ FreeForm Pro. And yes, other things like particle systems can come in handy, too.