DMT is slightly waxy and can be slightly sticky too. To make big crystals you should recrystallize and do a very slow evap. This is the
recrystallization tek I first used and it works great!
When doing a slow evap you may have some slight oxidation, but it shouldn't make a difference to the experience. Just put your solvent, after the re-x, into a glass and place a piece of cardboard covering the mouth, but slightly offset so the solvent evaporates more slowly.
Another way is cooling the solvent at a slow rate. So put your sealed container containing the saturated naphtha on a windowsill (if winter) and then into the fridge for a couple hrs, then freezer for a couple hrs, then back into fridge, etc. The slow cooling will form larger crystals than if shuving the solvent straight into the freezer.
Good luck!