The basic premise was (is) to built a plywood base framed by 2x1 inch softwood, for rigidity, and then to nail Sundeala board over the top, for sound deadening, ease of scenic sculpting, etc. See this post for more details/rationale.
Turns out that the differences in measurements – metric versus imperial – mean that the Sundeala tops are too short for the plywood base, meaning that there is a 3-4 mid-market gap where the baseboards join. Here’s a photo that explains this better.
And a close up…
What to do? I can’t bring myself to dismantle the boards and start again. I could fill the gap with filler, but this would affect the ability to separate the boards neatly if I need to move the layout. My solution is to simply tape over the gap with masking tape. If/when I do separate the boards I can then fill in the gap at each board edge.
Meanwhile the track that runs over the board joins will be soldered to screws either side of the join, which should mean that the track won’t be compromised by any of this.
Time only will tell whether this is a decent workaround or just daft.