Steve,
Thanks.
I recall reading that one and there is another one with full DIY details somewhere out there too !
Probably based on the same system, just another implementation
In addition to those, there is also a Polish made USB Dome Controller that is relatively cheap - $270EU = AUD$460 (it was $350EU last year)
http://www.scopedome.com/en/scopedomeusbcard.aspx
It appears to be a very well made unit and seems to support an encoder for dome positional feedback - they supply their ASCOM compliant software free of charge.
Just add motors and gears !
I think the project is a good idea, but I am not sure if recreating all the functions that are already available is necessarily a good one.
Use ASCOM for all of its existing functions and seek to add further functionality to ASCOM by catering for those things that arent already handled. That way it can work with any custom designed software and it can work with existing software that seeks to control common devices.
This then dictates how the controller hardware should be designed and the nature of the software driver/interface to the controller and any applications that will use it.
Cheers
Rally