River Coaster Update
The lower layer of the river now has it's own curves that differ from the upper layer, it's a more interesting shape for the whole coaster. The upper and lower layers but start and stop in the same positions so the tiles can still be laid in any order. The lower layer tiles also share common edges to make the cutting fast and simple.
The lower layer now runs all the way to the edges which makes it look much more like a continuing river this achieved by cutting the two halves of coaster and spanning across the gap with a spar underneath the coaster. I'm using the stronger 5 Ply BR grade birch plywood which is plenty strong enough for this 3x3mm spar. The spar locates into the lower layer of the coaster which is hidden under the top layer. Just for completeness I painted the spars black which makes it even harder to see them through the river.