I forgot to add, we didn't see it really cause they didn't computer model it, I remember reading a long time ago they choose to use "well known" trek ships like the Galaxy, Excelsior, and Miranda to CG cause back then, CG was very expensive so they could only afford to do a couple ships. By the end of the series is when we start to see the sabre and the steam runner. Because the Amby appeared a few times, it wasn't very remembered, so didn't get thought of when they were CGing ships. Remember the Intepid class (can't remember its name) that was in DS9 appeared about the same time the started using the CG Voyager more instead of the real physical model they had.
This is most based off a article I read once years ago, and some stuff I filled in, so take it as it is
BTW I can't wait for you to finish this amby, it looks great so far, I hope through your busy life you find time not just the Ent C model, but a TNG model, and a dominion war/PDW refit. This ship is by far I want to see the most