One turntable with two arms, or two turntables with one each - which would you prefer?
An Inquiry of this type is able to suggest that a New Plith is a requirement.
One turntable with two arms: This as a method has seen many Bespoke Built Designs to suit an individual's specific needs or wanted aesthetic.
or two turntables with one each: This can have various permutations, where one of them is for the use of Two TT's of the same design used with different Plinth Materials and the same Tonearm and Cart' used for both.
Either of the above, to suit one's specific needs, can require a Bespoke Plinth.
Plinth Materials are always going to surface when an Inquiry lends itself to potentially having to have Bespoke Equipment at hand to realise the method proposed.
@syntax Your statement is correct, My Granite Plinth which weighed in at 9 Stone, was produced as a design using professional services from a Stone Mason Company. There was no Middleman's mark-up, for the era it was produced, it was quite expensive, from recollection approaching £500, I'm sure another £500 was able to be added if Purchased through a Dealership.
When P'holz was in regular supply, it was approx' £150-200 for a Plinth Blank from an individual supplying Blanks, and even cheaper if sourced as an off cut through another source.
I would have selected P'holz over the Granite, if I knew what I do now, through the experiences of both in use.
Today I have selected P'holz for Plinth Purposes, over other owned Board Materials and other Structures available to me as a Plinth Material.
As said Sub Plinths in this material can be found selling at £1000, so sourcing and working with a Board of Densified Wood, if very cost effective.