I normally dry hop in a keg, using hop pellets in a fine mesh hop bag suspended from a welded nut on the lid. I typically wait with chilling the keg until after a week of dry hopping. The higher ambient temps should extract faster. The more vigorously I agitate the keg during that period, the more fine hop pellet material makes it through the mesh, which will eventually settle on the bottom. The first few pints will be green and harsh. It gets better after that.
2 weeks ago I didn't have another fine mesh hop bag and instead used a piece of very fine woven natural (unbleached) muslin from my wife's fabric collection. It is actually pretty substantial and quite thick, and you cannot see through it. I was amazed how much and vigorously I could agitate without getting the green flood in my beer, while it seems to extract the hop oils equally well. I'll have her sew a few bags out of that and maybe the next fabric weight down, if I can find it. I also have some really thin muslin that's more like very fine cheese cloth. I don't think that would be tight enough to hold the fine hop powder back.