For your budget-conscious precision honing needs, I present the DIY Laser Honing Guide, a.k.a. DILAHON.
Materials needed:
(1) A line laser diode module, like this one available at https://www.adafruit.com/product/1057 (https://www.adafruit.com/product/1057)
(https://cdn-shop.adafruit.com/970x728/1057-00.jpg)
(2) A 3xAAA battery holder, like this one available at https://www.adafruit.com/product/3287 (https://www.adafruit.com/product/3287):
(https://cdn-shop.adafruit.com/970x728/3287-02.jpg)
(3) A gooseneck stand, as is used in this IKEA JANSJÖ desk lamp:
(https://www.ikea.com/us/en/images/products/jansjo-led-work-lamp-black__0613277_PE686201_S4.JPG)
(4) Tape
(5) A paper print of the attached PDF
(6) Electronics solder
(7) narrow shrink-wrap tubing
(8) 3 AA alkaline batteries
Tools needed:
(1) Soldering iron
(2) Heat gun (or hair dryer)
(3) Scissors
How to build the DILAHON:
(1) If necessary, cut off any existing connector on the wires of the battery holder, and strip the insulation from 5 mm of the ends of the wires.
(2) Slip a 25 mm length of heat-shrink tubing onto each wire of the battery holder.
(3) Solder the wires of the battery holder to the leads of the laser diode module.
(4) On one wire of the battery holder, position the heat-shrink tubing over the solder joint, then use the heat gun to shrink the tubing in place over the solder joint.
(5) Repeat step (4), above, for the other wire of the battery holder.
(6) Load the 3 AA batteries into the battery holder.
(7) Using tape, affix the laser module to the end of the goosneck stand:
(https://photos.smugmug.com/photos/i-QjGvDzL/0/edce9dc7/O/i-QjGvDzL.jpg)
(8) Print out the attached PDF, and cut it into a circle.
How to use the DILAHON:
(1) Affix the circular angle guide to the leather honing wheel, with the 0 angle line oriented vertically:
(https://photos.smugmug.com/photos/i-ZqZdkW4/0/5040e798/X2/i-ZqZdkW4-X2.jpg)
(2) Turn on the DILAHON laser, and position it so that the projected laser line falls on the leather honing wheel at the desired position. Here the laser line is positioned for 12 degrees:
(https://photos.smugmug.com/photos/i-m5rf6w7/0/929b5c22/X2/i-m5rf6w7-X2.jpg)
(3) Remove the circular angle guide:
(https://photos.smugmug.com/photos/i-QL3hHbx/0/9116d073/X2/i-QL3hHbx-X2.jpg)
(4) With the knife blade kept horizontal (parallel to the ground for both roll and pitch,) position the knife edge at the laser line on the honing wheel.
(5) While keeping the knife edge at the laser line and keeping the knife blade horizontal, hone as usual.
This method takes advantage of our ability to judge and maintain horizontals and verticals with greater precision than we can judge or maintain arbitrary intermediate angles.
My typical results from unaided freehand honing are BESS values between 150 and 200. My first attempt using the DILAHON resulted in individual BESS measurements of 80, 108, and 110 (mean = 99.)
UPDATE: My latest test of the DILAHON resulted in individual BESS measurements of 73, 81, and 90, for a mean value of 81 -- a personal best.
An interesting idea, it can even be useful to check the inclination of the knife when the curved tip is sharpened.
I think your idea is good and it can be improved even more, I think that if you can somehow make the lamp stay fixed to the tormek you avoid that when moving the machine we should recalibrate everything.
I'm probably cheaper than you. Here's my version...
(https://image.ibb.co/ezxW95/New_Laser_Bracket.jpg)
... flipped around for the leather wheel side (different laser, same concept)...
(https://forum.tormek.com/index.php?action=dlattach;topic=3671.0;attach=2400)
... a combination of: laser w/ magnet, piece of steel, few stop collars, and a USB. Here's the original thread (https://forum.tormek.com/index.php?topic=3329.0) of mine. Jan and Rick have versions also.
It's a bit easier just to mark the side of the wheel with the angles, IMO.
I'm impressed with your BESS scores !