Off-topic (of request) but there are two tricks I use to have (e.g) walls built from a prefered side and not from the other.
1) When wanting to be outside of anywhere with convex features, build the/a corner last. Two walls meeting at an angle, that will enclose a space you don't want to be walled within, can be built up-to-but-not-8ncluding that corner, which is a diagonal passage, then ask for the corner as a final micromanagistic flourish and it will be built (if you've chosen a corner with a place to stand at all) safely from the outside as the seal is made. Local speleography (twisty turny caves, whatever pre-dig or post-digging cavities you have to work with) can usually supply you with handy points to put up such walls with a final (or indeed penultimate, etc) 'keystone' wall to build that serves your purpose.
2) If that's not possible (you wish to build yourself into a totally convex figure) or otherwise you don't want that fuss, set to construct a wall on the spot(s) you need to prevent building from, but suspend it immediately (if material choice is important for the real building site, make it a material item that is clearly not what you want to use in the true target structure(s)). Once the way is blocked (in the intended way) by the real wall, cancel the work-blocking wall.
A special variation is building a perimiter wall atop a lower layer of wall (with internal flooring) or out over a void (ditto). External convex corners need to be built before both corner-adjacent walls are complete. Though you can set one of them up - and indeed need to if it's a floating level, building a temporary floor in the other position for access and maybe first support. When the corner is built (and 'hangs off' the first corner-adjacent block) you can deconstruct any temp floor you needed to build and put that last wall in.
If it's a wall atop a wall without any inner floor, instead choose a block as much exactly opposite your access point (or blocks close to equidistant betwixt any two same-level accesses to the wall-top) and then once that's built, build the next adjacent pair, accessed from either side, and then the next next adj. builds, etc, until you have just one wall (per buildable access) to fill in. Creative scaffolding/catwalk access (that you later remove in a logical manner) can add options for you, depending on how much tenacity you can muster.
But there are other ways of doing this. It's just a matter of knowing where you want to get things to and how things need to go to get you there, working backwards in your mind if it's needing such a mental workout that it doesn't seem obvious from the start.