Thanks to renewed interest in this topic (by at least 1 person ) I created a TurboCAD drawing of the bracket arms as seen in Photo #2 in the original post, augmented with an additional cutout:
The rectangle at the bottom is 3 1/2" x 1/2".
The shaded area is a 3/4" counterbore rather than a through hole.
The 3 large dots represent the center points for all of the circular arcs that I originally drew on paper with a compass.
Distance of the right and left dots from the "origin": 3 1/2"
Distance of the upper dot from the "origin": About 2 27/32"
Radius values from the right and left dots: 3 7/8", 4 3/8", 4 7/8", 5 1/4".
Radius values from the upper dot: 3/8", 3/4", 2 1/4".
If you're more handy with scissors than a compass, I copied a 1:1 PDF version to my webspace at
If you make your own version of the bracket, the mounting distance between the arms will depend on the length and expansion range of the toilet roll holder itself. The arms must be close enough to prevent the holder from falling out when fully extended ... but far enough apart that the holder can be installed with a full roll of TP. A little trial and error will help you decide where to screw in the 3 1/2" x 1/2" x 1/2" mounting pieces.