l want to build a solid wood turntable

OK....I'll ignore all the shungite and etc., and approach this in a somewhat serious fashion....if $ is Not an object....

Waterjet a granite slab for the base.  I once approached the process with a 1" clear acrylic slab, but wasn't able to follow through with the project.

I was going to approach it with a direct-drive motor; in retrospect, a belt drive would allow for isolation, but an untoothed belt would allow for precision provided one could ensure near zero slip.

I'm a tangetal arm fan; 'nuff said.

Cart?  As said, $ no object.  Whatever one feels will make one happy...

As for support, pour a concrete column and place the above on it with sorbothane isolation pads under everything.

At the end of it all....if it doesn't make you happy....

Find another pursuit.

Oh, I forgot about the platter.....*tsk*

A machined lead alloy.  An alloy, to allow for strength but applying the mass of lead for stability....

All of this ought to be in a temp stabilized, dust free, near zero humidity cabinet that's allowed to come up to speed.

Remote cueing, of course.

An additional side cabinet to allow the lp to adjust to the 'play' space would be a +....but that goes without saying.....