NavList:

Hello David.

As has been noted, there are many free downloads to enable you to make your own astrolabe, but I do agree with you that the best way to learn about stereographic projections and their application to astrolables is to draw it out yourself and I urge that you rediscover your old drawing board.

You were evidently at Imperial College about ten years before me - though I was up the road in the Physics Department. I think by then they would have taken a very dim view of throwing darts from the College buildings!