Step H - straightforward, visible in photo in Step I.
Step I - the first try at putting these on wasn't very successful, as suddenly the wonky structure is having to pull together into a more rigid box or otherwise all the tabs won't fit into these side walls. Plus some of my slots weren't big enough (which I have now fixed). As above, I decided to punch the windows on the 2nd floor of the left wall, and to insert an extra window in the bathroom. Afterwards, I smeared glue into all the cracks of the left wall ground floor window diecuts, to seal it in place.
Step J - I've only balanced the third floor in this photo, it isn't tabbed in properly.
Step K - I discarded the closet door as I won't be using it, and put some filler around the inside of the door opening.
Then I de-constructed the shell in reverse order, starting the prep on each piece as it came off including staining, starting to apply filler to the edges that will show (inside of door ways for example), filling in a few cracks in the ceiling ply and doing lots of sanding. I LOVE my palm sander - it is absolutely wonderful and in seconds I can get the whole of a piece very smooth. I used an offcut of ply to test all slots and notches, and where they didn't seem wide enough I used a Dremel tool with a thin rotary bit to carve them a bit bigger (aren't power tools wonderful?).
Conversion of Right Wall: I have a purchased octagonal window so I marked a hole on the right wall, centred above the kitchen wall and hopefully high enough to allow a bath underneath. I used a coarse cutting disk in my Dremel tool to make the initial cuts, then cut through the last layers with a knife. I may use a bit of trim to make this window look more like the diamond shaped window lower down.
Conversion of Kitchen / Entry Wall: I cut this off because I am going to have a sales counter open to the main part of the shop. I will also cut off the fireplace wall and only use the top part of it to carry the overhang along the ceiling. I have left the Center Wall alone because I realised it is holding up the second floor!
Conversion of Front Wall: I cut out a large square opening which will reveal the store through the glassed in display window (porch). I centred this opening and left some wall on either side to act as the backdrop to the display window. This meant that I had to cut partway through the former French door, and almost all of the entrance door away. I used a knife to make these cuts but found it very difficult to get through despite repeated strokes and a new blade. Then I glued back the loose punchout pieces on the sides. Afterwards I filled in the grooves of the diecut with filler. (the soup cans were weighting down the glue parts while they dried.)
I have stained all three floors to give me the option of using them as flooring - although I haven't ruled out carpeting. I also stained the third floor bannisters - they aren't very satisfactory as despite a LOT of sanding they still look rough inside the punchouts. I also noticed that they aren't even punched out at the same height, but I've decided that won't be very obvious in the finished product.
So I think I am just about ready to start spraying on the sealer tomorrow. I went back to Focus and bought some more paint for the interior walls, and discovered a 'suede effect' ceiling paint that looks like a textured ceiling, so I am going to use that on the ceilings instead of the paint I bought yesterday.