I replaced a too-wide set of shelves between the doorways to the kitchen and the attic, then added an over-door shelf: Dinner dishes hadn't made it to the dishwasher yet, oh dear.
I had to leave room for the light switch, which made room for some other items:Cordless phone on a quickly-built angled stand, notepad, CO detector, the spot where I routed a shelf support, thinking the switch was a foot higher on the wall.... Oops! That gray thing is not a firearm; it's a solid-plastic training aid. But it couldn't stay there, as even it was too much temptation during junk phone calls. The other gadget is a tiny, French-made telegraph key. Quite a nice little key, in fact. Here, perhaps it will be handy if we receive any telegrams.
I put the short shelf, the vertical that supports it and the two shelves it is connected to together as a unit before proceeding with the rest of the assembly. This simplified the process considerably, though I am starting to think I need two more 4' long pipe clamps. (You can never own too many clamps).
There are two more doorways to bridge and I will have encircled the room. (And two boxes of books to be shelved). However, the shelves on the opposite wall are only temporary; it has an archway into the living room and my plan is to build new shelves on each side and at least one shelf along the wall above the archway. At least one of the temporary shelves will be moved to the living room: with the science fiction all shelved, there will still be science, technology, biography and history books in boxes, plus some mysteries (Sherlock Holmes, Travis McGee, Amelia Peabody) and a few others.
I'm considering a frieze of toy soldiers along the molding over the kitchen door; or is that too quirky?