Not An Observatory

But perhaps a more practical way to go from outside to observing faster.

This Canadian has another odd shaped telescope for which has designed a very clever way to protect his scope from weather while making it fast to get it open and closed.   Picture a box that closes over the telescope in its most relaxed position.   It is mounted on a hinge and when you winch it up your telescope is ready for action.  There are no walls so I still have to dress warmly but open is about 30 seconds ditto for close.  I just need a watertight 2.5' x 4' x 7' box open on one side to which hinges will go.  I wish there was a way for it to go completely flat 

Two great advantages compared to an observatory or the moving building design. Once down for the night it is only 4' high.  No sight line obstruction for our neighbors.   It is also easily moved when we move on to a hopefully magnitude 6.5 sky.  No concrete pad.

If you wanted to make something like that lid: 2.5' x 4' x 7' that was watertight how would you do it?  It sounds like an aluminum welding job.  It does not need to be thick.   There is only snow load on it and I would brush it off before it got too deep.  Thin because it should be light enough to pull a rope over it to lift it up.

Or fiberglass?  Sheets of it here are not very expensive.   I suppose that you could take sheets and turn them into a box with fiberglass cloth and epoxy to bind the corners together.   Probably not pretty until sanded and painted.

Fiberglass planter boxes!  But finding one deep enough is not easy. There is a company that custom makes them.