No it wasn’t, it was genes and it sat on his desk before being loaned out to the studio

It was loaned out in the run-up to Star Trek The Motion Picture. It was not loaned to the studio at the time of production of the original series. I'm talking about the ownership of the model back in 1964, not 1978/79.

No the model was made before any production, again documented and linked for source.

Filming of the first scene of "The Cage" took place on 24 or 27 November 1964 (accounts vary).

The 3-foot model was commissioned from Richard Datin on 4 November 1964. He received the blueprints on 7 or 8 November 1964. An in-progress version was presented to Roddenberry on 15 November 1964, with Roddenberry apparently requesting a number of changes, ie "more detail". The model was delivered to Roddenberry on 14 December 1964 while "The Cage" was being filmed in Culver City.

Therefore the model was made during production, not before.

Source for most of these dates: http://www.shawcomputing.net/resources/shaw/1701-33-inch.html

And even if the model was made before production of "The Cage" started, it doesn't negate my point, which is that the model would almost certainly have been paid for, and therefore owned, by Desilu or Norway as it was clearly a production/pre-production expense. It was used consistently throughout the run of the show, and was even modified to more closely resemble the 11-foot model. I find it inconceivable that Roddenberry would have paid for it out of his own, personal, pocket.

Again it’s documented, you’re simply making things up.

I'm not making things up, I'm speculating based on what I know of business and Roddenberry himself. Roddenberry was known to appropriate items that were owned by the studio for his personal benefit, eg when he took film clippings after the show was cancelled and sold them through his private business Lincoln Enterprises.

Roddenberry merely stating "I've owned it since the Desilu days" in a letter doesn't necessarily make it so. Note I'm not claiming he didn't own it, I'm raising it as an academic possibility. And, as I said, I have no problems at all with the model going back to the Roddenberry family once it's been recovered.