I created a prop - a control panel with many different parts mostly made from primitive shapes. The final piece looks good with all materials attached. When I export as a prop and then import back in - the materials I assigned are gone?!? 

I know I've seen certain props with various material assignments.  How do you create the material assignments?

Let's say you have a red ball and blue cylinder.  If you save these as an OBJ they come back with just a PREVIEW color for both. I want to keep the separate materials of each shape.  I don't find the grouping tool to intuitive - I've made some headway but the groups I'm assigning get lost when I export as a an OBJ. Is there some check box I need to use to get all the existing parts saved as a group of objects?  I've downloaded OBJs from the interent and have seen where different areas of the props are assigned different mats thus giving the user user the ablity to color it to their choosing.   I can't figure out how to do this....please help and thanks

The grouping tool can do this for you.
Select the ball object, open the grouping tool, create a new group (name doesn't matter) and choose "Add All" The whole ball turns red - all polygons are selected.
Now choose the button "Assign material" and type a new material name, e.g. "Ball"
You can remove the group, it was just a temporary container to hold the polygons that you wanted to select.
Do the same for the cylinder (choose another material name).
Now export as .OBJ and reimport. While the colors are "lost", the material names are not, and you can assign separate textures/shaders to the ball and the cylinder.

ok....If I make  a mistake how do you remove a material so that it doesn't show up in the material room as an option.

Also, does each object have its own group or can you assigne multiple objects to the same group - if so how? I keep trying to add more than one object (i.e. ctl click) but everytime I select an object it asks for a newgroup.  Tks so much.

 Multiple objects in the same group: not possible. You can turn a collection of multiple objects into a single object by exporting more than one object at the same time to an .OBJ file, then reimport the file. The reimported .OBJ is a single object - with multiple groups.

Removing a material is not supported in Poser itself. If you want to remove a material from a .OBJ file, the (free) UVMapper Classic by Steve Cox will do that. 

If you save an object to the Poser library as a prop,or figure you can also remove the material from the .pz2 file using a text editor or a CR2 editor. I use CR2Builder by kim99 for this purpose.

1. Create your object from the primatives
2. Open the grouping tool
3. Select the first primative from the props dropdown menu (the one on the main window or the Paramiters panel) it will go red and everthing else goes black.
4.  "Assign Material" as svdl discribes then click the "Add Material" and set this to the 1 you just Assigned.
5. Repeat steps 3 and 4 for each primative untill all are done then close the "Grouping Tool".
6. Open the "Hierarchy Editor" from the "Windows" menu.
7. Drag and drop each object one by one into just one of the other object.
8. Click the "Create Figure" button then click "OK" on the next pop-up panel and then name your new figure in the next and click "OK". This will create a new figure in the "New Figures" folder of your main Poser 7 Figure Librery. Close the "Hierarchy Editor".
9. Delete everything from the stage (or just create a "New Document")
10. Load the Figure you just created from the Librery.
11. Export the figure as an OBJ
12. Pat yourself on the back for a job well done!

I do appreciate everyone's help!  I've been dinking around with this and notice that I will need to be more granular on the mats I'm assiging as they all get combined on the re-import. For example I have 20 lamp lenses which I want to assign various colors. In Poser every single thing I select I can assign a separate color to the mat called "lens".  However I just now found out through trial and error (very time consuming...) that when I import everything back in I get just one instance of "lens" which means the same color will be applied across the board.  

Speaking fo boards...I'm going back to the drawing board on this and assigne each material its own name, lens1, lens2, lens3, etc.   What a freaking pain....thanks everyone!!! 

Megajax - what advantage is there in creating a new figure with this prop? Can't you just export it directly to an OBJ..? I amy be missing a step on this.  tks 

Quote - Megajax - what advantage is there in creating a new figure with this prop? Can't you just export it directly to an OBJ..? I amy be missing a step on this.  tks 

Don't really know, but when I created it as a new figure as discribed and exported it as an OBJ then reimported it  all the materials were still there, it was only 1 object but in the grouping tool it had all the individual elements still selectable. That was just how I was told to do it when I first started using Poser. And besides as a figure you can add bones in the setup room to things like switches and leavers.