Simply an addition and derivative of the work linked by PhysUdo
I have used these great river section with his section scaled to 55% for use with 15mm figures.
I made the longer sections and 90o to speed up making the longer runs I needed.
The 90o bend is just the two unique 45o pieces welded together, and the long run is 4 pieces welded together, One straight A version and one straight B version, then another A and B flipped to give a full run of variation.
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