Hi Catherine,
Sorry for the delay – had a sick kid for a couple of weeks over here.
Yes, it can be stored at room temperature for a couple of days so that would be absolutely fine.

Hi Kate,
Great question! This really depends on how many children are using the sensory bin and how much bacteria is being introduced to the bin – either by unclean hands or little tasters.
Freezing or reheating the flour will kill off bacteria and allow the sensory bin to be used for longer. Since I have 5 kids all from different homes using the bin, I tend to wash the toys each day (or every other day) and empty the flour/oil mixture into a large ziptop bag and freeze until we play again. This gets me at least one month of play, before I change out the sensory bin for something new.
If you don’t have the option of freezing or reheating the flour mixture, I would toss it after 1-2 weeks to be safe. (It might be safe longer than that – especially if the kids’ hands are clean, but I tend to be overcautious.)

absolutely – this is mentioned in the blog post but not the “recipe card”; I’ll make a note to update the recipe card for those who just skim the post.