Because the Time Lords were still figuring out bigger on the inside and time travel, this interior is basic and not as extravagant. 

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I think this looks like 1-st doctors TARDIS . I think You should add  more detail

 Well I would but here’s the caveat: the Doctor stole a Tardis that was in the museum which means it prolly was one of the OG’s. This is simply a mock-up of that because the Time Lords were still perfecting “bigger in the inside” and time travel. I purposely left out details here. Every first or second model of something new, never had exact detail until whatever it was, was completed and ready. See where I’m coming from?