I got all excited when I found the Pikon Telescope design last year, bought mirrors and misc. vitamins, printed out all the bits, and then gradually ran out of steam when I couldnt source the pvc pipe size required for the project at a reasonable price. Apparently it's a common size across the pond, but couldn't find anything in US that wasnt special order only for $20/foot. Kind of defeats the purpose of 3d printing a telescope if just the tube ends up costing more than an actual kit.
I've uploaded 10cm and 20cm sections with slip connections and a 10cm straight section. Quantity required will vary depending on the focal length of your mirror. You should be able to mix and match for an exact approximation of the perfect length.
I measured my printed Pikon end caps as having 12.45cm outer diameter, these tube sections have a 12.5cm inner diameter. I recommend printing a short test section and testing with your Pikon parts to get the size dialed in for a snug fit.
I've gotten as far as printing the sections, but havent had time to finish assembling or test. The sections fit together pretty snugly, but I'm going to strongly suggest you glue the joints. Again, I have not completed my build or tested these in the field yet. Also- test yours over something soft, concrete and mirrors dont play nice together
Mine are printed Quick and Dirty style at .25mm layer height with brim on a Taz6 with the standard .5 nozzle. I usually print with three perimeters, and the tube walls are 2mm thick, so my walls are essentially solid. Z-Seam is randomized because... Cylinder. These tube sections feel pretty sturdy, especially when all interlocked together, but like I said- currently untested.