×(15,16) to (16,17), though in my demo, the original fluff blob expanded beyond that.

×Drag some of the puffs over to where you want the fluf blob to form, but don't worry about the blob forming yet. Then hang out around the checkpoints in column 18 until turn 11 or so to keep the puffs more towards the eastern end of the room. Make your way over to the checkpoint at (14,15). This is the real crucial position of the room. You need to be at that checkpoint at about the same time the threat clock hits 30 (I ended up with one move after). If you do that, puffs forming on the vents won't have enough time to get you before you're safely back on the checkpoint, and puffs from last cycle should be out of the way by then.

×Skell's idea generator: http://forum.caravelgames.com/ideasGenerator/view
Challenges Scoreboard: http://forum.caravelgames.com/challenges.php
Level map viewer: http://forum.caravelgames.com/map.php
Tactical DROD game: http://forum.caravelgames.com/tsspreview.php
(Note: Requires Flash)
Room Element Search tool http://forum.caravelgames.com/roomsearch.php
(Search through all published holds for rooms with various elements.)
Room position Heat Map http://forum.caravelgames.com/heatmap.php
DROD has a wiki! http://drod.wikia.com/wiki/Deadly_Rooms_Of_Death_Wiki
Skell's super cool list of turn sequence stuff https://docs.google.com/document/d/1QS9Vk3xsd4jlGF23J8p7c2IM5cmhwmoe6eCEaaAn8jY/edit#heading=h.ocovx14zokm4

It's not listed in "help", but [attachment] will embed the whatever image is attached to a post.