Yes, everything had to be made or purchased and altered. When they made Trials and Tribbulations they couldn't really recreate the chairs. My earliest TV memories are an astronaught wiping the camera lens on the moon and the shot taken from the back of the Enterprise nacelles. At the time, Trek fx were AMAZING! Part of the suspension of disbelief was making allowances for the back of the nacelles sort of "blinking into existence" as the ship got closer while orbiting a planet. I think people were a bit more creative back then and that their minds filled in the missing pieces without even noticing they were doing it. As a child, it was one of the things that attracted me to the show. The budget for the show was similar and sometimes slightly lower than other shows at the time, but other shows didn't have to try and recreate the 23rd century in every shot. If they needed a table and chair, they could just get one from the prop department or just go buy one. Trek had to design and make the table from scratch. Lost in Space was a kiddies show that could have someone put on a lobster suit when they needed a monster. Trek was made for a more adult, and a more sophisticated, audience. Lobster suits would not due.
You have to remember that in the late sixties, the attitude was "just put in some blinking christmas lights and it will look like a space ship". This philosophy can still be seen as late as the eighties in the first Alien movie. You will notice that most of the panels are nothing but blinking lights. There was a lot of pressure for Trek to become a kiddy show like LIS, but they resisted the pressure. Ok, maybe they bowed to the pressure when they made "Spock's Brain", but generally they resisted. There were no other shows that looked as good as Trek at the time. The use of colors was to attract viewers who had just purchased color TV sets. Trek was the most popular show among people who had just purchased a new color set. Compare it to anything made in black and white and you will kind of get the idea. The rail around the bridge, for example, was painted red. Look at it in "The Cage" or the subsequent clips in "The Menagerie" and you will kind of get the idea. The uniforms were made in multiple colors for the same reason. Trek popped when compared to anything else on the air at that time. It still looks pretty good, even though it is obviously aged.
