Well... after a night of work (and using my breadboard version as basis) of soldering and drilling I have a prototype! I've used off-the-shelf components to house the board and everything fits nicely... secure... and works perfectly.
The next version will have an override switch (since the current version will only activate when there is data on the serial port) to allow power all the time.
Now is time to use this version as a test for how many amps it can push out... note I'm still using my computer power supply (which is still powering this machine I'm surfing on!) and all is well.
Finally... The going price for one of these will be AUD$65.00.
Anyone wanting one can leave a comment on this post or email me at stevenhoefel at hotmail dot com.
I've also written a new client app... very basic... controls the train that you specify.