Well the model is not truly hovering over the base but it does have that appearance.
Looking at the new Shadow Spectres model from Forge World there is a pic of one of them hovering above the base. I have been working on my new counts as Shining Spears and thought it would be nice to make some of them over above the base instead of sitting down on it.
First off I drilled a hole in the base, much like I was putting the model down on it
Then I filled the hole with Green Stuff until it was even with the base. A bit to much is not going to hurt either. The extra will just go into the rod and stabilize it some more.
Then I placed a hollow brass rod into the base. I decided that I wanted to be able to remove the models from the base so I am using a sleeve method.
Next I drilled a small hole in the middle of the back of the model to put the solid wire into. Pretty much as if I was going to rod the model.
Now it comes time to bend the solid rod 90 degrees. I wanted a gentle curve so I would bend a portion of it and move down the rod until I had the 90 degree bend I was looking for. One thing you have to keep in mind about this is give yourself enough room from the back of the model to the bend where it will fit. If you make the bend to shallow you will find it running down the back/legs of the model and ruin the effect that you are trying to get.
Once the solid rod is in place in the model I slide it down into the hollow tube.
Once the test fit is good to go I build up green stuff around the hollow tube to support it.
I will paint the rod and hide it when scenery with it comes time but I like how it gives the impression that the model is floating above without the rid coming out of the foot, which on models like this the feet and toes are on the small side so drillling into them can be a bit rough (I did one through the toe and gave up as it destroyed to much detail).