The overall dimensions are accurate enough with just the regular sold-with blade. The finish is a little rough, and it bites quite easily, but in terms of being close enough to CAD for it to work it does the job. If the finish bothers me I tidy it one way or another. Sadly HDPE just goes gummy and nasty when using fine-finish (fine grit sandpaper for eg) methods, the coarser the clean up often the better. I used a fence for the long cuts, which was a piece of wood clamped to the bed, spaced 6cm from the blade in this case.

To drill the holes I clamped the HDPE pieces to the alu bulkheads and transferred the positions, then used woodworking bits to do the counterbores/sinks etc.

Don't have time/need now, but after the champs I may look at getting a different, more suitable blade for the tablesaw. Intend to work more with nylon as I can source it easily, and from past experience that doesn't cut too nicely with the existing disc.