Big day, the first round of focuser parts have been sent to a printer. They are being printed in Onyx–nylon combined with chopped carbon fiber–for 1.4x the strength and stiffness of ABS. There is no real unit testing yet, since the focuser is itself a unit test of the tertiary housing. No doubt a lot of smaller unit tests will come from this initial run. The draw tube is expensive to print, so we will look at options for this. I did find a source of aluminum tubing the correct diameter, but this of course presents its own assembly challenges so maybe 3d printing is still the cheapest way to go overall.
All the rest of the parts that go into the focuser are either from McMaster-Carr or part of the GSO dual-focuser assembly. Will order from McMaster-Carr tomorrow.