So I’ve looked at several enclosure lids and they all are focused on maximizing access to the machine from both the top, front and side.
What is interesting is the different angles people have used.
My question: Is this a personal preference, or is there a structural element that users are designing around?
I have tried to depict the various approaches that I have seen
I think the tip-up door can be eliminated if you just leave enough headroom above your machine and don’t attach much to the ceiling of the enclosure.
When I put the cover on my machine, I’ll have a way to completely remove the whole cover/top for CLEANING and maintenance. Expect that when you put on a cover to keep the dust in (that doesn’t go out the vacuum), then the dust will accumulate in there.
Wouldn’t it be more advantageous to have extra height in the enclosure all the time? Since you’re normally working above the bed especially if you have an XXL. I’m not sure I understand the use case for removing the top unless you have a very short enclosure.
I’ll have extra height all the time, but removing the top will allow me to run wires and other things. For instance, I had to “hire” my grandson (he’s six) to change the filter on my a/c, because it sits above the router. 
I have a door that is the same style that you have.
A couple pointers.
Make it so the door opening allows you to get to your x axis belt tensioners easily. You’ll also need a significant amount over room on from for the spindle to come all the way forward with a dust boot on it.
Piano hinge across the too and you will need some strong gas struts. They get very heavy very fast.
When I made my enclosure. I screwed both side pieces together. I laid out the shape I wanted on the side of the doors. Then I cut them together. This way everything lines up perfect and is symmetrical.
personally I would minimize the “bump my head to the top” occurrences when having to reach all the way behind the shapeoko. …
early on I decided to have vacuum (and later water cooling) hoses come in high from the back (and not the top) which was (20/20) a good idea… but if you have the vac etc come in from the top, then some of these designs will get in the way. Anyway assume you’re optimizing how much space you open up on the top side.
I suppose another consideration is the weight of the part you lift up, which makes your “option A” kind of suck. Its likely easiest to make, but for the space it clears up on the top (only half way) it has the most weight to pivot; your option B does much better there, it can open more space with less weight.
BTW, +1 for asking before building just anything.
I just finished the cut for option b. Turned out halfway decent. Marking up a window now to cut. Thanks for the pictures I was looking at various builds trying to figure out the best way as well. Your post pushed me to make the cut today.
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Appreciate everyone’s comments and feedback here. The benefit of writing up your problem and then sleeping on it, is you have all sorts of revelations…
I realized that I will not be able to flip the lid on top of the box as @Cslon just did as I do not have the ceiling height (Low ceilings). So I have landed on either Option A or Option C. I have included the pictures explaining my thought process, so that months from now others can look at this and think out their enclosure design
The one thing to note that Option B and C give that Option A might not, is a surface to mount the gas struts to. Hoping someone on this forum can validate that.
