Print 5 copies of "Electra_6_mod.STL" - either all the same colour, or in 5 different colours. This will give you a total of 30 modules to slot together.
On our Replicator and using ABS, the print settings were - 10% infill, 0.3 mm layer height, 2 shells, 100mm/s feedrate, 150 mm/s travel, extruder 230 deg C, platform 110 deg C; and no support.
[Note: As a test, the orange pieces were printed with 0% infill and 1 shell; and they worked (but are not as strong as the others).]
Here are the assembly instructions; see "Assembly.JPG".
1) Make a ring of 5 modules - keep the biggest angle inside the ring to make a pentagon. If you're using colours, then these should all be different and in any order you want.
2) On the outside of this ring fit 5 more modules to make 5 triangular rings around the pentagonal ring. The rule for the multi-coloured version is "match the opposite corners of triangles and pentagons" - see "ColourMatch.JPG".
3) You now have 10 modules in a star shape. Add another 10 to complete the next 5 pentagons, i.e. another two to each pentagon. Use the colouring rule, above, to decide on the colour.
4) Nearly done... You now have a hemisphere; add another 5 modules to complete 5 more triangles.
5) Finally, fit 5 modules to make the final 5 triangles and pentagon. You might find it useful to loosen some of the adjacent modules before inserting the last few pieces.
6) Squeeze all the joints together.
7) If the joints are loose, try a bit of glue. I was luckily and there's enough friction to hold the model together.
Good luck and happy assembling.
This model relies on friction (or glue) to keep the joints together. The tightness of the joints will probably depend on the size of your extruder nozzle, print settings and filament. If you have loose joints try scaling down the model, if they're tight scale up...
If you want to be adventurous, you could try one of the other untested STLs - one should give a spherical outer shape, the others add small spheres/points on the vertices.
I've also experimented with locking tabs, but they tended to give surface features on the prints.
The Stripey Electra was printed on a Replicator 1 using filament swapping - 3dfilaprint's Orange PLA 0-62% & 68-78%; Fabadashery's Galaxy Blue PLA 62-68%; 3dfilaprint's Glow-in-the-Dark Blue PLA 78-100% of Replicator print progress. Mainly Makerware PLA defaults, with changes - 1 shell, 7% infill, 205% extruder temperature, 100mm/s extrude. Each set of 6 modules took ~75 minutes to print, and I needed 5 of them (i.e. 30 modules). The model is ~17cm across.