I used a scrap piece of wood that is around 10" square and 7/8" thick for my lamp. I used a spade bit to drill a hole in the center. My lamp arm is made of steel and has a screw mount inside one end, so all I need is a way to secure it to the base and I can screw it together from underneath.

I added some EVA foam rubber feet to the bottom of the base, so there's room for the cord underneath. 

I ended up drilling a second hole (not shown) next to the center hole for the USB cord to come through. I did it after the lamp was built, but this would have been a better moment.

I drilled three holes in my steel lamp arm: one at the top, middle, and bottom to attach the track to the arm with screws.

Sand the track lightly to help with paint adhesion. Paint really doesn't want to stick to this stuff! I had the most success when I started with a plastic primer spray paint and then did a few top coats of metallic black.

I screwed my lamp arm to the base, and did a test-fit with the track to be sure my screw holes were in the right places. This took a little trial and error but I'm happy with the result.

I took the track back off again to mount the LEDs and diffusion gems.

For diffusion, I'm using these plastic crystals from Amazon. They are fairly lightweight and have an interesting texture. I'd considered using glass pebbles but they'd likely be too heavy and pull the track out of shape. These crystals are perfect. I ordered the 16x22mm size. One bag was the perfect amount for my 5' track.

I used clear silicone caulk to fix the LED strip and gems to the track. It will stick to the silicone casing around the LED strip, and also give me a firm setting for the gems. It dries clear, so won't block the light.

This brand takes 5-7 days to fully dry, but I had a decent hold after 24 hours and was able to assemble the lamp by moving carefully.

I pressed the LED strip into the caulk, then added more on the top and pressed the gems firmly on top, making sure they were all stuck down. Be generous -- really goop it on there.

These gems make a truly wonderful diffusion material. I can't spot individual lights at all.

Once the caulk was dry (enough), I screwed the track back onto the rod at the top, bottom, and middle. I had to do a little adjusting because a fully loaded track weighs quite a bit more than the empty track weighed, but it worked out well in the end.

I put a large piece of black heat shrink over the QT Py to keep it from shorting, and also to hide it from view. I hot glued it to the back of the track near the lamp base, with the capacitive touch wire and USB port facing down. 

For the capacitive touch sensor I decided to use copper tape. I cut some pretty shapes out of a copper tape sheet using my Cricut vinyl cutter. I chose the Adhesive Foil setting and cut one large starflower to use as the main button, and a few more smaller ones just for decoration.

I stuck the big star to the lamp base with the capacitive touch wire underneath, pressing down firmly and smoothing with a straight edge to get a good electrical connection. 

I tested touching it with my toe and it works to control the lamp, even through my socks!