While I’m working on this project, I’m also researching the tools and techniques used by the instrument makers who made these astrolabes. The two period manuals I am working from assume a certain shared level of knowledge, and do not mention tools or engraving techniques, except in passing.
I am finding the art of the period a better resource; in particular, I found a very nice portrait by Hans Holbein the Younger:
(Note: WikiMedia is listing this image as Public Domain, if anyone claims the rights to the photograph, please contact me at the email to the right and we can discuss it)
The original image can be found here.
The subject of the portrait is shown with several tools and a partially completed sundial compendium similar to those described in Hartmann. The tools for designing and laying out the lines of a sundial are the same ones that would be needed in designing and laying out an astrolabe.
Identifiable in the portrait are two straight-edges (one on the table, one hanging), two scribing compasses (on the table and hanging), a set of dividers (by the hammer on the right), a scriber (in front, right of center), some scissors and some other tools whose use is not immediately evident.
My friend Miguel, of Spanish Peacock was nice enough to make me a very nice straight-edge out of hardwood, based on the one in the painting:
A bit later, I stumbled across a two pairs of scribing dividers at a Harbor Freight sale.
I’m currently looking into buying a good scriber, and I will be ready to start playing with brass. I have neither the time nor skill to build a complete astrolabe from scratch, but I’m thinking a brass version of one of the climate plates might be instructive to attempt.