Tony et al,
In the case of the 3D pantograph by David the accuracy of the laser
pointer itself isn't important.
At first the beam is adjusted through the (nodus of) the style and a point
on the dial.
Then this beam is shifted parallel to itself until it shines on the mirror.
The beam then is in
Here's a simpler proposal.
Transfer the declination lines and hour lines of a horizontal
sundial onto a transparent sheet.
Mark a small circle on the centre of the mirror.
Support the horizontal transparent sheet, rotated from north
to south, with its nodusvertically above the centre of the
I like it!! Printing the dial artwork on transparency film should work
well. Rub it down onto a thin sheet of glass supported in a frame, perhaps
with a film of water or the like to keep it in place. The frame would need
to be accurately leveled and oriented, but could easily be clamped in
