Hi Marco,
When I offered to make an arm board for you I forgot that you have never fitted my Bearing Base Plate. This serves two purposes, it stiffens the base area of the alluminium plinth and also raises the platter height by 6mm just enough to overcome the height restraints for most arms, I believe.

I have never made a two-piece arm board as I feel that the two pieces, can only degrade the stiffness in this crucial area and cause the arm board to act like a diaphragm.
There is mention of the need for absolute rigidity in this area in one of the SME technical bulletins.

The problem with the SL1200 is that there is a large hole to bridge when the existing arm/VTA assembly is removed. Unless this hole is sufficiently bridged with a rigid assembly then the thin metal double layer approach held together by three small screws, is not going to do justice to an expensive arm and/or cartridge.

I have however designed a single piece arm board specifically for the SL1200, with a suitable depression, which could fit all requirements. It would be machined from alluminium or brass and would be much thicker than the ones now available. This “thickness” is designed to be below the top surface of course.

There is marginably more machining to do but I will put a price on it of A$295.00 for the Alluminium version Inc postage. The unit will be a drop-in replacement for the existing Arm/VTA assembly.
Each arm board by it’s very design will be specific to a particular tone arm and spindle distance.

I have a SL1200 development test bed so I can accurately set off the required spindle-to-arm column centre distance with long-reach vernier calipers for each arm board I machine.