Not sure I like that - cover arm seems too long.  Trouble is, although this is 3D CAD software, the display is always 2D and that makes things a bit difficult.  Also, things like the domed cover are quite difficult to construct in 3D.  Of course, I have to do it for printing but seems a chore just for a diagram.  Measuring the RPi and USB plug and from where it fits with respect to the camera, the main casing will be 140mm high and this is the height shown in the diagram so it wouldn't be out of place.  The other point is how strong the gearbox is in the stepper motor and the windage on the cover.

Due to the height of the stepper motor drivers on the RPi HAT the diameter of the casing is going to have to be about 140mm diameter if it's a cylinder.  If it wasn't for the rotating lens cone it could be oval, as I've done in the past.  It might be possible to arrange the RPi etc. below the bottom of the lens cone but I doubt it would be worth the effort.  Also, if I go for 140mm I can use the lens cone I've already printed if I add a bit extra on the top and maybe a bit extra on the bottom to provide a better overlap to keep wind driven rain out.  Furthermore, the RPi can be moved up into the cone and save 20mm on the height.  I think with this system I can get the motor drive for the lens cover above the lens cone and reduce the length of the arm but this remains to be proved.

A photo showing the lens cone with extensions.  Cone rotates with lens for focussing.  Print not tidied up yet.

Tidied up the lens cone and now printing the main casing - just a cylinder 138mm OD and 2mm thick by 120mm high.  Printing time 2h 10m.

Finished wiring up the HAT for the new component positions.  Main casing still printing...  Should be ready for testing the remote focussing soon   Maybe tomorrow.  Be quite some time before I'll be able to test on the stars - cloud forecast for the foreseeable future!!

Main casing printing finished and now just waiting for it to cool.  Making healthy creaking noises as parts of it come off the bed as it cools...

Here's a photo from above showing the ASC in casing showing how the RPi & Hat fit in.  If it it turns out that I need a separate RPi for the weather station, there is plenty of room for it

Completed casing side view.  The main casing still has the brim from printing.  The lens cover motor in its casing should easily fit above the lens cone while still being below the lens.

I'm now looking into the mast mounting and how the ASC works are fitted into the casing, the run of the power cable etc.  This is a new way of mounting the ASC casing and presents new problems, particularly with the power cable.  Previously I have run the cable inside the mast tube but this is much more difficult now.  It would also mean drilling a hole in the lower mast tube.  I know many people just tie the cable to the outside of the mast and maybe I shall have to do the same, at least for the time being.  This would certainly cure one headache

The ASC casing needs attaching to the "works" to keep everything aligned properly.  One way is shown in the cross-sectional diagram below which I think may be easier than a ring and spokes from the aluminium heatsink block or camera which was my first thought.

Still not sure.  And the diagram above is wrong - the focus motor comes almost out to the casing.  The focus motor support could be extended out to the casing and two more "legs" could fully support the casing.  Also, having the heatsink clear would allow heat to rise up to the lens and help with dew heating and the casing would be supported further up which is more effective.  This method would use less filament too. 

Motor bracket and casing support.

Printed and fits perfectly

I think I can simply glue the main casing onto the base that also forms part of the bracket that holds the weather station wind instruments.  I have elongated the hole in the mast tube where the power cable came through and I reckon I can again run the cable inside.

A couple of photos of the casing glued to the base/bracket.  I'll tidy it up and fill hollows and also improve the inside fillet.  ASA dissolved in acetone.

That seems to be the main casing sorted out and now looking into the lens cover motor housing.  This is a first attempt to see how it fits.  This has the stepper motor driving the cover arm directly.  Previous design had a pair of gears giving a slight step down ratio.

Forgot to allow for the filament thickness and the motor wouldn't quite go in so I've changed the design and printing it again.

Gradually advancing the design of the lens cover motor casing to fit it as close to the lens as possible to reduce the length of the arm.  These are just test prints to check fit, hence the low "wall" round the edge - just high enough to be sure the motor will fit in.  The bottom end will need a curve to fit onto the main casing where it will be glued on.  I shall make a hole in the casing for the motor wires.

This is almost right - just needs another mm or two offset from the main casing.  But I've noticed one thing - if this casing is in one piece and glued onto the main casing I won't be able to remove the lens cone to gain access to the "works".   So I'll redesign it in two parts to fit one inside the other.

Two part design.  The top part housing the motor fits over the bottom part which will be glued to the main casing.  The latter just needs amending to allow for the curve of the main casing.  I'll sort that out when I've confirmed the motor housing parts fit together snugly.

Now printing the bottom part and thinking it looks a bit small.  I might make both parts bigger where they overlap.  Also, though the bottom part does print on end without support material, the print was soft and wobbling around as it printed though the final result doesn't look too bad

Reduced printing speed to about half and redesigned the parts 10mm bigger in the smallest dimension.  Also added a bit to the lower part to fit the curved main casing.

Not quite right...

Redesigned the lower part.

Fits alright now   Nice and snug - can turn the unit upside down and the top part with the motor doesn't fall off.

Now printing the main part of the lens cover.