I don’t know that the dimensions are all that critical, and you can get an idea of the sizes from the microphone. The walls, ceiling and bottom have to meet. No holes or gaps. So construction accuracy is critical.
But that’s not the way I did it.
I did it using common parts given you live near a Harbor Freight or other large hardware store. My Home Depot has 24-inch pipes pre-cut and that would have created a completed sound studio before lunch.
https://forum.audacityteam.org/t/too-compressed-rejection/52825/22
It knocks down for storage, as I said, under the bed when you’re not being a voiceover artist.
Koz