Here is a neat little shelf to hold one or two folding/extendable lamps over your treadle.
The first picture shows the shelf from aways back. The second close up.
The shelf is made from standard 3/4" board. In this case, I had a small piece of mahogany in my scrap bin. The shelf itself is 15" x 5". The corners have been curved so they aren't sharp, and to improve the appearance a bit. A 1/2" hole has been drilled at each end, and an extendable lamp has been inserted in each hole. This shelf is screwed to another board, 4" deep, which attaches to the wall for support. This is visible in the first picture.
The shafts on these extendable lamps are not standard, but most are close to 1/2". If the fit is tight, simply bore it a bit larger by using sandpaper on a dowel rod. You want the fit to be just a bit loose, but not sloppy. The lamp should be easy to turn, but not trying to fall over.
I can usually find a couple of these lamps in garage sales on any weekend, for a couple of dollars. I ran into a problem here, because there is a wider shelf above the light shelf. Some of the lamps were too high… you couldn't fold them up because the arm joint wouldn't fit under the shelf. Fortunately, I had two nice matching white sewing machine lights I had ordered from a sewing supply outlet (Brewers or PD 60… both wholesale only). These have shorter arms and worked just fine. You can see in the first picture how they just fit under the shelf above.
In my sewing corner, I have the treadle on one wall and a parlor treadle on the adjoining wall. This set-up provides excellent light to either machine, or both at once if I am using the top surface of the other for positioning, trimming, etc.
In the second picture, you can see how the shelf is handy to keep an extra spool of thread, a pin cushion, a cup with markers, etc.