I agree that Durham's is not the best stuff for this. It is indeed very hard and difficult to work with once it sets.
I use WS foam roadbed. You might get a bit of that for filler. It's easy to cut with a knife or even scissors. Another option might be thin craft store foam board, which is easy to cut with a sharp knife.
It takes an iron man to play with a toy iron horse.
Durham's can be really tough to sand and level, I would fill with pieces of homasote or use plaster (not joint compound - it shrinks and cracks too much) or just leave it and fill with ballast.
Jay
C-415 Build: https://imageshack.com/a/tShC/1
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I'm using Homosote roadbed from Cascade Rail Supply. Because I'm using mostly #8 and #10 turnouts and the only turnout pads they currently have available are for #6's, I'm left with that empty triangle in the roadbed where the route diverges.
I'm thinking it would be really easy to fill these triangles with Durham's rather than cutting pieces of roadbed to fit. Anybody have an opinion one way or the other on this idea?
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