I plan to elaborate later on a seemingly promising way to support a 100º book cradle using standard heavy duty 90º brackets...

I look forward to seeing that! (And showing it to my brother.) I haven't built anything yet.
That is indeed a good price, shipping not included though, 3/16" rather than 1/8" acrylic, I'm not sure if that could be significant, and I'm not sure whether one sheet would be large enough for both pieces? At that price, and no impact on shipping, probably might as well buy two sheets anyway.dpc wrote: ↑05 Apr 2021, 16:47I think what you want is ACRYLITE P-99 Non-Glare Clear acrylic sheet. Here's some on eBay that's cheap.
The point of using 100º angle was to avoid the need to use anti-reflective acrylic?? But of course, if the final price is right that is perhaps less important, although there could be some albeit maybe very slight loss of sharpness. But is there a good reason for using a 100º platen with anti-reflective acrylic? And if you do you use a 100º platen, why not use a 100º cradle if the design outlined above works?
Smartphone Tripod Mount... but I'd need something that would either grip each side of the smartphone,...
On that detail, in David Landin's design the left-hand book cradle brackets rests against an MDF bar screwed to the movable board mounted on the draw runners, depending on the thickness of that board possibly screwed from below. In his design on the right side he used the electrical terminal blocks, which he found satisfactory with 90º brackets. You could try that with 100º brackets if you wish, otherwise I was thinking that a similar MDF (or whatever) bar could be used, if necessary screwed from below, either screwed into alternative holes for reasonably quick adjustment, or alternatively a fixed bar set at the maximum anticipated width, with spacers (either of different widths, or variable in number) between the fixed bar and the edges of the 100º brackets, which could be changed very quickly.Doranwen wrote: ↑07 Apr 2021, 22:55"On the 100° cradle ... I had an idea for the adjustment method for different size books. If we drilled little holes in the base plate, and used movable pegs, it would be just like adjusting for the shelves on your bookcases. Of course, in this case, the holes would be much closer. They could even be non linear to get them closer, since they would just have to catch the angle brackets somewhere. Something like 1/8" diameter, 1" long metal pegs would do it. Even 3/4" long would work fine."