I don't remember exactly when, but many years ago I built a tiny fiddle yard. Possibly because it was so small, it remained hidden away from sight whilst more ambitious, but ultimately flawed successors came and went. It's had a few minor modifications over time, but the basic design remains.

As a temporary fiddle yard for the new layout, it's just fine. Gives me time to think about the best design for the long term. The yellow pins are an easy way of making removable 'buffer stops' to prevent stock rolling off the track and onto the floor. This works fine for 2mm scale and DG couplings.

The underside view below shows the socket (at the top in the photo) intended for a support leg, should it ever be required to be part of a layout on trestles. It also shows how bits have been added over time to accommodate longer stock and to make the interface with a layout more robust. Good job these crude changes are not so obvious from the normal viewing angle!

Power is transmitted to the turntable tracks by rods sliding into brass tubes - one at each end of the layout. This works fine for DCC, where all rails are live all the time, but would require changes for layout operation with DC.

The fiddle yard also works fine as a short test track - either with DC or DCC, requiring little space to set up... 650mm long by 85mm wide, except for the interface panel, which is currently 260mm wide. I may trim that a little to match the baseboards for the new layout.