If you can't do the time, don't do the crime!

First thing to do is to build the woodwork. Make sure your base is big enough to give a stable platform for the finished consruction.
Cut out balsa and glue together. If you like, you can add fancy dowel bits as I have done but it isn't necessary. For the dowel I used errrrrrr......dowel. Drill into woodwork then push in dowel that you have pre cut to size.
Now for the cage

Cut strips of plasticard with points on one end so that they fit together nicely and then glue them to a plasticard disc and then glue another disc on top trapping the strips between the two discs.

Now make rings out of more plasticard strips by gluing the ends together so they overlap slightly. As you can see, I used four rings. Now slide these over the strips bending them down as you go and glue in place when your happy with the position.
Cut a plasticard disc out which is slightly larger than the opening at the bottom. Add the chain which the cage hangs from and paint the whole thing black.
You can now add a live figure or a skeleton as I have done which is from the old GW skeleton pack. Paint the figure then glue to the disc you made for the bottom then slide this into the cage and glue base in place. You can now dry brush the cage silver if you like or leave it black.
You can then add all bits and pieces if you like like a padlock and re-enforcing bits.
Fit cage onto woodwork and your away.