Assemble the above shelving unit (or one of your choosing) but put the bottom shelf on the very edge so you end up with a complete rectangular frame.
You also need some thick polycarbonate (a.k.a. plastic!) sheeting like this (find it in the window aisle at Home Depot) that is at least large enough to fit over the front (ie. top) of the frame:
I chose a .93 gauge so it was thick enough not to be too flimsy. To cut it, trace the shape of the frame and then, using a straight edge, take a razor over one of the lines a few times until you have a nice groove. Now line up the plastic on the edge of a table and snap the unwanted piece off. Do this to adjust the length and width of your plastic. Your plastic top should fit your frame so all edges are flush.
Next, you'll put a piece of 1"x1" pine (or other cheap wood) in your plastic to hold the plastic in place:
Cut the wood (hand saw comes in handy here) so that it just fits the inside edges of two parallel sides of your frame. The shorter it is than the inner edge, the more your table top will slide around, so try to make it pretty precise and err on the side of "tight".
Put the plastic on top of your frame, and mark where you'd like to attach the wood and the plastic. You'll need four short screws or nails. With a drill bit, drill holes (slowly!) through the plastic:
Once you have your holes, fasten the wood to the plastic table top. Don't try to screw or nail right into the plastic--it will crack!!!
Now your plastic will fit, wood side down, into your table:
See how the wood fits right in? Nice.
There's your blogger friend, Stephanie:
Oops, are your corners too sharp? Just snap off little pieces with the razor until they aren't too sharp. We don't want the kids cutting themselves on your state-of-the-art light table, right?
You'll need a hole on the bottom of the back side of your table so your electrical components can inconspicuously exit the light table. Drill one or two holes in the back (I used a spade bit).
Lastly, I painted the inside white on the sides that weren't already so I'd have maximum reflective power.
You'll need a shop light or other lamp that will fit into the light table:
We started out with some colored lights:
But since we don't want to see the lamps, I used wax paper (and later changed to parchment paper), taped well, to turn the top from transparent to translucent. This will be something I need to problem solve later on. Don't they make some spray paint that makes clear glass look smokey? I wonder if that would work.
Total time, including the Home Depot trip: 3 hours!!!