This is a covered version of http://www.thingiverse.com/part:3404 with two parts : an outer bracket with hinges to fit with other Elements, and an inner part holding the lamp socket that locks into place.

This elaborates on http://www.thingiverse.com/thing:7836, making it easier to replace the light-bulb, and also fixing the dimensions so that the hook on the back of the socket is not obstructed.

It is designed to work with the decorative polyhedral Elements to build lamps for diffuse lighting http://www.thingiverse.com/thing:6281. The hook on the back of the lamp holder makes it easy to hang lamps flexibly around the room. I plan on attaching several truncated-icosahedral lamps to a chain which can be draped over other furniture. If all goes as planned, the plastic shell will also protect the light-bulbs, making it possible to leave these lamps on the floor with minimal risk. The goal is to design a diffuse light source that is both beautiful and resilient, so it can be moved about and played with easily.

Animated GIF showing assembly : https://lh5.googleusercontent.com/_KLnvj61OxTo/TbW9cClPdgI/AAAAAAAACqQ/S-lV1ZcRLI4/dothis.gif ( shown with shade made from http://www.thingiverse.com/thing:5961 )

I went through several stages of prototypes when designing this, which can be found in all_intermediates.zip. The final design is in all_revised.zip.

As you can see in the exploded view, three pieces comprise the actual cover for the lamp holder, while a hexagonal piece with hinges is designed to be the socket which attached to the lamp cover.

I would assemble a truncated icosahedron out of pentagonal and hexagonal Elements of your choice, leaving one hexagon out. Print out part 1, and finish the polyhedron by placing it with the top of the print facing the interior of the lampshade.

Then, print the three parts for the socket cover. These will go around the socket http://www.thingiverse.com/part:3404, and are held together with super-glue.

Before you start, make sure the bulb you are using can slide comfortably through part 1. If it cannot, find a smaller bulb or consider using the version that is not designed to be easily replaced : http://www.thingiverse.com/thing:7836. I do not know if the heat from incandescent bulbs will melt ABS, I use CFLs which seem to be safe.

Thread on the back cover part [5] before you attach the cord to the socket. Make sure it is oriented with the bottom of the print facing toward the plug. Also slide on piece [4] at this time, again with the bottom of the print facing toward the plug ( or toward part [5] ).

If your lamp cord does not already have a plug attached, add this now.

Be careful to insulate any exposed wiring with electrical tape when you do this:
Attach the lamp cord to the socket part http://www.thingiverse.com/part:3404. This socket has a back piece that rotates and clamps the cord onto two pins, making an electrical connection.

The lamp cord I use is thick ( low gauge ), and you want to test to make sure the socket makes a good electrical connection with the cord ahead of time. Place a bulb in the socket and plug it in. If it flickers when the socket is jostled, your connection is not secure and you may need a thicker cord. If you have a good electrical connection, unplug the socket and remove the light-bulb. Finalize the connection between the cable and the socket with some electrical tape.

Put the socket part http://www.thingiverse.com/part:3404 inside part [4] such that the socket faces toward the interior of the lampshade.

Super-glue the locking piece [3] over the lamp socket. You may want to line up the locking pins with some land-marks on the cover, if you want things to line up cleanly and clearly when the socket is locked into place.

Slide on the back cover part [5] over the cable and super-glue it into place.

Insert your blub in the socket and carefully slide the socket cover into the lampshade. Plug in the lamp and enjoy.

note on hinge clearance : The hinges can sometimes be a little tight. Make sure the first layer isn't pressed too far into the build platform. A compressed first layer will propagate up and make part of the hinge wider, decreasing the clearance. These parts are designed to fit tightly and may require pliers to assemble. If all else fails, removing some of the pins on the hinges can make assembly easier.