OK, I wanted to make a head for my character. So, in MED I thought I would take a sphere and then turn on vertex mode and move vertices around until my sphere looked more like a head. Then I realized it was really hard to be perfectly symmetrical with this so I decided to select all the vertices on the right half of the sphere and press delete. I clicked OK, OK to the prompts and then proceeded to try and model the left side. When I got it to a good shape I clicked the mirror button to create a mirror image of it. Then I rotated that and tried to place it perfectly on the other side. When I took a look at my work in the 3D preview window and in the engine preview I saw big gaping holes in my head! I'm not sure what I did wrong. Is this not a good approach to modeling a head for a character?

Within MED it is a good approach, although you have to choose a restriction with the restrict button (two double arrows) to mirror and move it properly. You have to switch the normals of the mirrored part. Maybe, that's the reason why you see the holes.
Its better to model such things in other programs like blender. Look for 'modeling a head with blender', or something like that.

I think that MED can be come handy when you need to create really simplistic models but if you want to create more complex models (the head for example) I recommend you to use a third party software like Blend(FREE), 3ds max or Maya. MED is a good software but is to features limited and the work-flow is slow.

Pappenheimer... I understand how to set the movement restriction, but "switching the normals of the mirrored part" is confusing me. I'm not sure how to do that? (I checked the online manual to see if it discussed this, but couldn't find it.) I just did a really simple test of taking a sphere, cutting it in half, copying it, pasting and then mirroring the pasted copy. After this I moved it out to the right a little. The outside of the mirrored sphere is dark grey in the gourad shaded preview (with draw backfaces checked) and the inside is light grey. It is the opposite on the original. When I uncheck draw backfaces and rotate the camera around behind the mirrored half sphere I can see a hole through it. When I rotate around the original I don't. I probably won't use this to model heads (looking at Blender), but I would like to understand how to use this mirroring function correctly in case I need it. Thanks for the help.

Thanks, 3dworld... I am trying to study Blender to see what I can accomplish with it.

It is a button, called 'Flip normals'. You see the names of the buttons, when you move the mouse cursor over it and stop. It is near the buttons 'Subdivide' and 'Extrude'.

The flipped normals only happens when you clone any part of the model in an application like 3ds max. I notice that for example you create a robot in 3ds max then you make a clone mirror of the arm and when you export that model from max to MDL the mirrored arm has the normals flipped.

3dworld... that's good to note, although I'm not sure what happened in my case because I don't have 3ds max. I just used MED. As best I can tell it flipped the normals as part of the mirror operation.

Yes, that was it Pappenheimer... I flipped the normals and the hole disappeared.

Thanks for the help...