You should be able to estimate the size based on the DIN connector, which obviously fits into the back of the TG.
I ran this sucker on my late-model Sony monitor (on the VGA port). The result went something like this:
(exagerated to make a point):
Monitor: "I see you have properly formatted Horizontal Sync at 15 KHz"
Charlie "YAY!"
Monitor: "I see you have properly formatted Vertical Sync at 60Hz"
Charlie: "YAY!"
Monitor: "Unfortunately, I can't run that slowly!"
Charlie: "AGGH!"
The RGB and/or Composite video work great (and the audio is a given). I can run 3 TV's at the same time, if I also use the RF output of the TG itself.
Not too sure it would be cost effective to sell, though.
Don't understand the "how do you make it" question...you lay out a PCB based on the schematic, have it made, buy the parts, and populate it; just like any PCB. Or did I mis-understand the intent of your question?
Charlie