Flat pyrex baking tray things with glass lid like this.
Also have one with a plastic lid but i always put some aluminium foil over it to keep the fumes from eating the plastic lid.
Ofc a flat bottom on all of them else you will have a bad time.
Usually in the corners some dmt stays leftover but then i usually just throw another pull ontop and dont bother with scraping the corners. Just flush the naptha around to get the dmt out of the corners and then refreeze. At the very end i scrape the corners or i just wash it with drinking ethanol to get the rest.
I recommend having closed containers else your whole freezer will smell like naptha forever.
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