I really wish I'd taken some - any! - pictures during the table saw process but it was at a local HO modeler's shop and we were fairly busy. As I recall, each piece was initially cut longer than required by quite a bit, and then attached to a wood spacer. Then cutting was done with the spacer against the fence, so all measurements were from the fence and included the spacer. Final step for each was removing the PVC from the spacer and trimming off the ends to remove the screw holes and cut to length.
For the planning process, I used Adobe Illustrator as that is the program I used to generate the laser cut support structure. I started with the layout of the elevator in question, arranged representative PVC to get an idea of where things needed to go, and then started trimming from there. Modeling was also done in Fusion 360 to try to catch mistakes before starting everything.
Initial layout of PVC pipes:
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Planning in Fusion 360:
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