Finally received my bicycle tyre valve caps yesterday (the previous order were "lost in transit" so, progress was delayed somewhat.)

These are plain aluminium, but various colours are available - this could be useful if you wanted to allocate specific knobs to certain functions.

However, I opted for these ones - I think they match the overall style of the "control panel" of the layout.

The uncouplers and points are brass rod controlled, no electronics are involved.  Adding these caps to the ends of the brass rods gives the impression of something more "high tech" than is actually going on though(!)

I cut some small panels from 0.5mm plasticard sheet, to cover the rather rough apertures that the brass rods protrude through, the point switches had individual panels and the uncouplers had two shared panels with three apertures in each.

There was a fair bit of calculation and measuring involved in making neater openings for the wire shafts, holes of 1mm were drilled at either end of the calculated "throw" of each switch (these were longer in the case of uncouplers than of points.) Then, the plastic between each pair of holes was cut away and the opening sanded smooth to create the linear aperture for the rod to slide along.

The valve caps were filled with epoxy.  When dry, holes were drilled to accommodate the brass rod ends.

I'm really pleased with the end result:

Next job is to attach the controller to a suitable bracket, watch this space....