I am playing with Metaball and would like to know how to hallow the middle of it, can anyone help please ??? 

If you alt-click (I think)  on the create metaball icon it creates a negative one! Top tip is to instantly assign your negative meta to a different selection group (changing it's wireframe display colour in the process) and then duplicate to produce further negative metas. That way you can easily keep track of which are pos and which are neg.

ok Thanks Gog for your reply :)))

FYI, There's a similar (identical?) metaballs modeler in Carrara, I haven't gone in to check for differences, but you might want to also pick up Carrara 3D Basics on Purplus for a ridiculously low price, and then you can use the Metaballs modeler from there, in case it has more features (I dunno if it does, I just know that it's neat there too). These are likely based on the same Metaballs modeler from the days of Metacreations (which went Mega-Cremations years ago), so there's a chance you can see the same features and shortcuts in either.  You can find the link to Purplus at www.thebest3d.com/carrara  (sorry, the other boxes like CS3 and C4 sold out long ago)

I really like Bryce's metaballs.. it does take some practice to get something right, but it's a lot of fun too. Adding color to one ball and a different color to another makes some nice blending effects.

You might want to try out CB Modeler Pro too for similar model effects. It's not metaball, yet used with metaballs, one can model some very nice stuff. The models in CB Modeler Pro tend to be hollow. Here's the link to it, and it is free. http://www.cbmodelpro.com/

Yes, great one indeed. In the same category of drawing shapes to build blobs and then painting a texture map you also find Curvy3D and Archipelis Designer.

Curvy is more into drawing curves, like Splines in Illustrator styles, and a few curves are used to build tubes and blobs and you can re-edit the curves. Archipelis is more into drawing or tracing an outline of existing background image, and see the blob built from it, and immediately be textured with that background image. (you can change the image/texture later, but the uv maps are there and that's what counts)

thanks alot guys for you help!!!  :)))

You might consider naming your negative metaballs........"meta-neg#1" or somesuch. This helps with all objects especially when you are dealing with dozens of objects or a complicated wireframe.
For those with very little experience I've found that you can make really cool 'organic' shapes with them but you need to think BIG. In other words, don't be afraid to use hundreds of them to make a really smooth organic shape.

In Windows its actually Shift+Click, but I'm sure you got that.

Another FYI for this suubject - when creating a group of booleans (negatives & positives), if you select one or more Negative Metaballs and just group those together, the negative effect will not work anymore.

You can group negatives and one or more positives together and everything will be fine.

I know, weird. But, something to keep in mind.