When you're building an arch out of multiple stones, there is a stone at the top which is referred to as the 'keystone'. Now, the keystone isn't necessarily more important; it can be larger and heavier, as I understand it. If any of the stones is missing, the arch will be unstable, but the keystone gaps two little half-arches. The pressure it provides pushes on the stones it's adjacent to, and they push on the ones adjacent, etc., until the force downward of gravity upon the arch's stones is distributed and countered by friction.
All these little designs -- the inventory script and the Engrishifier and such -- feel like nearly-finished arches. Several stones were set, but then some key point, some significant missing structure, some thing was missing, and I realized that the form wasn't stable, the props couldn't be pulled out from under it.
Maybe I just need to design more. Maybe I just need to know more.
Maybe, while I'm lamenting this, I should go implement the wordshifts on the Engrishifier.