But I wouldn't know where to go from there and I wouldn't know how to make a physical one.
Are there any OCW-courses (or similar) on the subject? Preferably with a hands-on approach :)
here is the 6809 (my favourite of the ones above):
http://www.zimmers.net/anonftp/pub/cbm/documents/chipdata/68...
You could go several routes to make one, first build a software simulator so you have something to validate your design with, then either use an FPGA or use wire wrapping like the author of the OA did (that's possible but also very very time consuming, and if a cpu is your first project is going to be a very frustrating experience).
http://www.amazon.com/gp/product/0262640686?ie=UTF8&tag=...
Theres a tech talk about the book:
http://video.google.co.uk/videoplay?docid=765404376202115650...
[1] http://books.google.com/books?id=u5kIA7iyfl4C&lpg=PA276&...
http://www.timefracture.org/D16docs/wire_wrap.html describes the practice of wire-wrapping, the technique used here.