I think some stretched sprue rods for fillers followed by a little sanding could address these nice gaps! That would be my first approach - stretch to about the diam you like, cut to length, soak in thin cement 20 sec or so, lay into gaps wet and let completely dry - and then scrape and sand a little. IF the rods are a snug fit, scraping should bring them down to surface nicely.
Alternatively, if you have some thicker styrene sheet, you could cut a few strips and wedge them into those gaps and follow up the same.
Hope this does not happen with my little KT coming in!
Bob
