Or maybe he goes to the room, gets the Mirror, and looking into the Mirror to correct himself, draws the circle just right.
(Since he does want to be able to make a Philosopher's stone, not just to get one - he wants 'mass-produced immortality'. And he had suggeted to Hermione that magical objects could be used to draw objects more precisely (only they were discussing a different object). And he had already used a supposedly-significant stone in battle in a least-magic-demanding way. And we haven't seen even in Rowling's world that the Mirror can only show 'real-sized things', so it can potentially magnify them.)
New chapter!
This is a new thread to discuss Eliezer Yudkowsky’s Harry Potter and the Methods of Rationality and anything related to it. This thread is intended for discussing chapter 102.
There is a site dedicated to the story at hpmor.com, which is now the place to go to find the authors notes and all sorts of other goodies. AdeleneDawner has kept an archive of Author’s Notes. (This goes up to the notes for chapter 76, and is now not updating. The authors notes from chapter 77 onwards are on hpmor.com.)
Spoiler Warning: this thread is full of spoilers. With few exceptions, spoilers for MOR and canon are fair game to post, without warning or rot13. More specifically: