I've a 70mm f=500mm surplus lens and a plastic refractor focuser, so why not make a simple refractor for fun?
Hey, don't go away first, let's see the result here:
They are taken handheld with my Canon 450D! Minimal processing has been applied, and notice that the chromatic abberation is really low for this cheapy lens! This is to my surprise for sure!
The tube is from a bubble bottle, my kids used up all the soap inside and so I cut it to fit the lens and focuser there.
In order to avoid poor alignment, I flushed the lens cell all the way to the bottle, so you see how the lens cell sit inside the tube and there should not be "any" misalignment.
Similar strategy was used to fit in the focuser, again since it sits inside all the way to the "shoulder" of the bottle, "no" misalignment could be possible.
The visual view is not bad either, given a Tele Vue diagonal plus a high quality 82 degree eyepiece. :-)
An interesting and fruitful project.