Hi everyone - after a suggestion from one of the folks here (http://www.thingiverse.com/thing:106329) this model has been remixed as a christmas tree ornament.
The STL files print a sphere 100mm in diameter. The top hemisphere comes in two versions - one is just a plain solid hemisphere, and the other has space in the middle to put in an LED - your choice of which one to make.
[EDIT 17 Jun 14] just posted some photos where I finally got around to adding LEDs - the "trench" piece in the middle looks cool laser cut from 3mm clear or opal acrylic with four LED's around the equator, plus a fifth LED in the laser dish. As an alternative to laser cutting, try 3D printing the middle from semi-translucent flouro filament
Also posted solidworks zip files - enjoy!
Print out the hemispheres, the middle spacer and the two locating pins, then glue them together. Some of the trenches overhang a little but it prints fine without support - 10% infill is fine.
The LED version takes a standard 3mm LED - push fit into the middle the laser dish and solder a resistor in series. I used an old 5V phone charger to power mine, with 5 x LED's and a 330 ohm resistor.
Use hot-melt glue to hold 4 x 3mm LED's and resistors in place in the middle (use the trench/equator piece with a cross shape to position LEDs in a star shining outwards) and run clear twin core wire up through the hole underneath the hanger loop, to both hang the ornament and power the LED's
The 'laser' is a work in progress and will probably need to make changes - at the moment assembly is quite fiddly/fragile while supergluing the parts together - print some spares just in case.